1 | # _________________________________________________________________________ |
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2 | # |
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3 | # Coopr: A COmmon Optimization Python Repository |
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4 | # Copyright (c) 2008 Sandia Corporation. |
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5 | # This software is distributed under the BSD License. |
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6 | # Under the terms of Contract DE-AC04-94AL85000 with Sandia Corporation, |
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7 | # the U.S. Government retains certain rights in this software. |
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8 | # For more information, see the Coopr README.txt file. |
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9 | # _________________________________________________________________________ |
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10 | |
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11 | from __future__ import division |
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12 | |
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13 | __all__ = ['Expression', '_LessThanExpression', '_LessThanOrEqualExpression', |
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14 | '_EqualToExpression', '_IdentityExpression' , 'generate_expression'] |
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15 | |
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16 | from plugin import * |
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17 | from pyutilib.component.core import * |
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18 | from numvalue import * |
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19 | from param import _ParamBase |
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20 | from var import _VarBase |
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21 | |
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22 | import sys |
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23 | import copy |
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24 | import logging |
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25 | import StringIO |
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26 | |
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27 | logger = logging.getLogger('coopr.pyomo') |
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28 | |
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29 | class Expression(NumericValue): |
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30 | """An object that defines a mathematical expression that can be evaluated""" |
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31 | |
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32 | __slots__ = ('_args', ) |
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33 | |
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34 | def __init__(self, name, nargs, args): |
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35 | """Construct an expression with an operation and a set of arguments""" |
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36 | NumericValue.__init__(self, name=name) |
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37 | self._args=args |
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38 | if nargs and nargs != len(args): |
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39 | raise ValueError, "%s() takes exactly %d arguments (%d given)" % \ |
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40 | ( name, nargs, len(args) ) |
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41 | |
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42 | def __getstate__(self): |
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43 | result = NumericValue.__getstate__(self) |
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44 | for i in Expression.__slots__: |
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45 | result[i] = getattr(self, i) |
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46 | return result |
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47 | |
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48 | def pprint(self, ostream=None, nested=True, eol_flag=True): |
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49 | """Print this expression""" |
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50 | if ostream is None: |
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51 | ostream = sys.stdout |
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52 | if nested: |
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53 | if self.name is None: |
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54 | print >>ostream, "Unnamed-Intrinsic" + "(", |
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55 | else: |
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56 | print >>ostream, self.name + "(", |
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57 | first=True |
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58 | for arg in self._args: |
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59 | if first==False: |
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60 | print >>ostream, ",", |
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61 | if arg.is_expression(): |
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62 | arg.pprint(ostream=ostream, nested=nested, eol_flag=False) |
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63 | else: |
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64 | print >>ostream, str(arg), |
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65 | first=False |
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66 | if eol_flag==True: |
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67 | print >>ostream, ")" |
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68 | else: |
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69 | print >>ostream, ")", |
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70 | |
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71 | def clone(self): |
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72 | """Clone this object using the specified arguments""" |
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73 | raise NotImplementedError, "Derived expression (%s) failed to "\ |
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74 | "implement clone()" % ( str(self.__class__), ) |
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75 | |
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76 | def simplify(self, model): |
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77 | print """ |
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78 | WARNING: Expression.simplify() has been deprecated and removed from |
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79 | Pyomo Expressions. Please remove references to simplify() from your |
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80 | code. |
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81 | """ |
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82 | return self |
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83 | |
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84 | # |
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85 | # this method contrast with the fixed_value() method. |
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86 | # the fixed_value() method returns true iff the value is |
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87 | # an atomic constant. |
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88 | # this method returns true iff all composite arguments |
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89 | # in this sum expression are constant, i.e., numeric |
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90 | # constants or parametrs. the parameter values can of |
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91 | # course change over time, but at any point in time, |
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92 | # they are constant. hence, the name. |
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93 | # |
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94 | def is_constant(self): |
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95 | for arg in self._args: |
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96 | if not arg.is_constant(): |
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97 | return False |
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98 | return True |
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99 | |
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100 | def is_expression(self): |
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101 | return True |
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102 | |
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103 | def polynomial_degree(self): |
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104 | return None |
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105 | |
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106 | def __nonzero__(self): |
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107 | val = self() |
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108 | if val: |
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109 | return True |
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110 | return False |
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111 | |
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112 | def __call__(self, exception=True): |
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113 | """Evaluate the expression""" |
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114 | try: |
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115 | return self._apply_operation(self._evaluate_arglist(self._args)) |
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116 | except (ValueError, TypeError): |
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117 | if exception: |
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118 | raise |
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119 | return None |
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120 | |
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121 | def _evaluate_arglist(self, arglist): |
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122 | for arg in arglist: |
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123 | try: |
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124 | yield value(arg) |
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125 | except Exception, e: |
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126 | buffer = StringIO.StringIO() |
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127 | self.pprint(buffer) |
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128 | logger.error("evaluating expression: %s\nExpression: %s", |
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129 | str(e), buffer.getvalue()) |
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130 | raise |
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131 | |
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132 | def _apply_operation(self, values): |
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133 | """Method that can be overwritten to define the operation in |
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134 | this expression""" |
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135 | raise NotImplementedError, "Derived expression (%s) failed to "\ |
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136 | "implement _apply_operation()" % ( str(self.__class__), ) |
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137 | |
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138 | def __str__(self): |
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139 | return self.name |
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140 | |
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141 | |
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142 | class _IntrinsicFunctionExpression(Expression): |
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143 | __slots__ = ('_operator', ) |
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144 | |
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145 | def __init__(self, name, nargs, args, operator): |
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146 | """Construct an expression with an operation and a set of arguments""" |
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147 | Expression.__init__(self, name, nargs, args) |
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148 | self._operator = operator |
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149 | |
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150 | def __getstate__(self): |
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151 | result = Expression.__getstate__(self) |
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152 | for i in _IntrinsicFunctionExpression.__slots__: |
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153 | result[i] = getattr(self, i) |
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154 | return result |
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155 | |
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156 | def clone(self): |
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157 | return self.__class__( self.name, |
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158 | None, |
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159 | copy.copy(self._args), |
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160 | self._operator ) |
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161 | |
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162 | def _apply_operation(self, values): |
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163 | return self._operator(*tuple(values)) |
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164 | |
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165 | |
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166 | # Should this actually be a special class, or just an instance of |
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167 | # _IntrinsicFunctionExpression (like sin, cos, etc)? |
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168 | class _AbsExpression(_IntrinsicFunctionExpression): |
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169 | |
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170 | __slots__ = () |
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171 | |
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172 | def __init__(self, args): |
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173 | _IntrinsicFunctionExpression.__init__(self, 'abs', 1, args, abs) |
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174 | |
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175 | def __getstate__(self): |
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176 | return _IntrinsicFunctionExpression.__getstate__(self) |
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177 | |
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178 | def clone(self): |
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179 | return self.__class__( copy.copy(self._args) ) |
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180 | |
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181 | # Should this actually be a special class, or just an instance of |
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182 | # _IntrinsicFunctionExpression (like sin, cos, etc)? |
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183 | class _PowExpression(_IntrinsicFunctionExpression): |
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184 | |
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185 | __slots__ = () |
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186 | |
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187 | def __init__(self, args): |
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188 | _IntrinsicFunctionExpression.__init__(self, 'pow', 2, args, pow) |
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189 | |
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190 | def __getstate__(self): |
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191 | return _IntrinsicFunctionExpression.__getstate__(self) |
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192 | |
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193 | def clone(self): |
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194 | return self.__class__( copy.copy(self._args) ) |
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195 | |
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196 | def polynomial_degree(self): |
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197 | # Right now, all _PowExpressions are considered to be |
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198 | # non-polynomial, even though there is a special case where |
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199 | # _args[0] is polynomial and _args[1] is constant and a |
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200 | # non-negative integer. I am still choosing to return |
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201 | # "nonpolynomial" because most consumers (like expression |
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202 | # compilers) do not recognize that pow could actually be |
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203 | # polynomial. |
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204 | return None |
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205 | |
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206 | |
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207 | class _LinearExpression(Expression): |
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208 | |
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209 | __slots__ = () |
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210 | |
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211 | def __init__(self, name, nargs, args): |
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212 | """Constructor""" |
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213 | Expression.__init__(self, name, nargs, args) |
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214 | |
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215 | def __getstate__(self): |
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216 | return Expression.__getstate__(self) |
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217 | |
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218 | def clone(self): |
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219 | return self.__class__( copy.copy(self._args) ) |
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220 | |
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221 | def polynomial_degree(self): |
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222 | # NB: We can't use max() here because None (non-polynomial) |
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223 | # overrides a numeric value (and max() just ignores it) |
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224 | degree = 0 |
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225 | for x in self._args: |
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226 | x_degree = x.polynomial_degree() |
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227 | if x_degree is None: |
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228 | return None |
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229 | degree = max(degree, x_degree) |
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230 | return degree |
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231 | |
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232 | |
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233 | class _LessThanExpression(_LinearExpression): |
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234 | """An object that defines a less-than expression""" |
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235 | |
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236 | __slots__ = () |
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237 | |
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238 | def __init__(self, args): |
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239 | """Constructor""" |
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240 | _LinearExpression.__init__(self, 'lt', 2, args) |
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241 | |
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242 | def __getstate__(self): |
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243 | return _LinearExpression.__getstate__(self) |
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244 | |
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245 | def _apply_operation(self, values): |
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246 | """Method that defines the less-than operation""" |
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247 | return values.next() < values.next() |
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248 | |
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249 | |
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250 | class _LessThanOrEqualExpression(_LinearExpression): |
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251 | """An object that defines a less-than-or-equal expression""" |
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252 | |
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253 | __slots__ = () |
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254 | |
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255 | def __init__(self, args): |
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256 | """Constructor""" |
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257 | _LinearExpression.__init__(self, 'le', 2, args) |
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258 | |
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259 | def __getstate__(self): |
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260 | return _LinearExpression.__getstate__(self) |
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261 | |
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262 | def _apply_operation(self, values): |
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263 | """Method that defines the less-than-or-equal operation""" |
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264 | return values.next() <= values.next() |
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265 | |
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266 | |
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267 | class _EqualToExpression(_LinearExpression): |
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268 | """An object that defines a equal-to expression""" |
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269 | |
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270 | __slots__ = () |
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271 | |
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272 | def __init__(self, args): |
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273 | """Constructor""" |
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274 | _LinearExpression.__init__(self, 'eq', 2, args) |
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275 | |
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276 | def __getstate__(self): |
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277 | return _LinearExpression.__getstate__(self) |
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278 | |
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279 | def _apply_operation(self, values): |
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280 | """Method that defines the equal-to operation""" |
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281 | return values.next() == values.next() |
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282 | |
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283 | |
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284 | class _ProductExpression(Expression): |
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285 | """An object that defines a product expression""" |
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286 | |
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287 | __slots__ = ('_denominator','_numerator','coef') |
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288 | |
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289 | def __init__(self): |
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290 | """Constructor""" |
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291 | Expression.__init__(self,name='prod',nargs=None, args=None) |
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292 | self._denominator = [] |
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293 | self._numerator = [] |
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294 | self.coef = 1 |
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295 | |
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296 | def __getstate__(self): |
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297 | result = Expression.__getstate__(self) |
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298 | for i in _ProductExpression.__slots__: |
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299 | result[i] = getattr(self, i) |
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300 | return result |
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301 | |
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302 | def is_constant(self): |
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303 | for arg in self._numerator: |
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304 | if not arg.is_constant(): |
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305 | return False |
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306 | for arg in self._denominator: |
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307 | if not arg.is_constant(): |
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308 | return False |
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309 | return True |
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310 | |
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311 | def polynomial_degree(self): |
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312 | for x in self._denominator: |
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313 | if x.polynomial_degree() != 0: |
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314 | return None |
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315 | try: |
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316 | return sum(x.polynomial_degree() for x in self._numerator) |
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317 | except TypeError: |
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318 | return None |
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319 | |
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320 | def invert(self): |
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321 | tmp = self._denominator |
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322 | self._denominator = self._numerator |
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323 | self._numerator = tmp |
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324 | self.coef = 1.0/self.coef |
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325 | |
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326 | def pprint(self, ostream=None, nested=True, eol_flag=True): |
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327 | """Print this expression""" |
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328 | if ostream is None: |
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329 | ostream = sys.stdout |
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330 | if nested: |
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331 | print >>ostream, self.name + "( num=(", |
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332 | first=True |
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333 | if self.coef != 1: |
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334 | print >>ostream, str(self.coef), |
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335 | first=False |
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336 | for arg in self._numerator: |
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337 | if first==False: |
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338 | print >>ostream, ",", |
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339 | if arg.is_expression(): |
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340 | arg.pprint(ostream=ostream, nested=nested, eol_flag=False) |
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341 | else: |
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342 | print >>ostream, str(arg), |
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343 | first=False |
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344 | if first is True: |
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345 | print >>ostream, 1, |
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346 | print >>ostream, ")", |
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347 | if len(self._denominator) > 0: |
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348 | print >>ostream, ", denom=(", |
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349 | first=True |
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350 | for arg in self._denominator: |
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351 | if first==False: |
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352 | print >>ostream, ",", |
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353 | if arg.is_expression(): |
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354 | arg.pprint(ostream=ostream, nested=nested, eol_flag=False) |
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355 | else: |
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356 | print >>ostream, str(arg), |
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357 | first=False |
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358 | print >>ostream, ")", |
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359 | print >>ostream, ")", |
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360 | if eol_flag==True: |
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361 | print >>ostream, "" |
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362 | |
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363 | def clone(self): |
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364 | """Clone this object using the specified arguments""" |
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365 | tmp = self.__class__() |
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366 | tmp.name = self.name |
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367 | tmp._numerator = copy.copy(self._numerator) |
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368 | tmp._denominator = copy.copy(self._denominator) |
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369 | tmp.coef = self.coef |
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370 | return tmp |
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371 | |
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372 | def __call__(self, exception=True): |
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373 | """Evaluate the expression""" |
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374 | try: |
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375 | ans = self.coef |
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376 | for n in self._evaluate_arglist(self._numerator): |
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377 | ans *= n |
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378 | for n in self._evaluate_arglist(self._denominator): |
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379 | ans /= n |
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380 | return ans |
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381 | except (TypeError, ValueError): |
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382 | if exception: |
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383 | raise |
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384 | return None |
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385 | |
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386 | |
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387 | class _IdentityExpression(_LinearExpression): |
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388 | """An object that defines a identity expression""" |
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389 | |
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390 | __slots__ = () |
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391 | |
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392 | def __init__(self, args): |
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393 | """Constructor""" |
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394 | arg_type = type(args) |
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395 | if arg_type is list or arg_type is tuple: |
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396 | Expression.__init__(self, 'identity', 1, args) |
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397 | else: |
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398 | Expression.__init__(self, 'identity', 1, [args]) |
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399 | |
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400 | def __getstate__(self): |
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401 | return _LinearExpression.__getstate__(self) |
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402 | |
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403 | def _apply_operation(self, values): |
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404 | """Method that defines the identity operation""" |
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405 | return values.next() |
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406 | |
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407 | |
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408 | class _SumExpression(_LinearExpression): |
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409 | """An object that defines a weighted summation of expressions""" |
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410 | |
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411 | __slots__ = ('_coef','_const') |
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412 | |
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413 | def __init__(self): |
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414 | """Constructor""" |
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415 | _LinearExpression.__init__(self, 'sum', None, []) |
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416 | self._coef = [] |
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417 | self._const = 0 |
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418 | |
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419 | def __getstate__(self): |
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420 | result = _LinearExpression.__getstate__(self) |
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421 | for i in _SumExpression.__slots__: |
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422 | result[i] = getattr(self, i) |
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423 | return result |
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424 | |
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425 | def clone(self): |
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426 | """Clone this object using the specified arguments""" |
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427 | tmp = self.__class__() |
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428 | tmp.name = self.name |
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429 | tmp._args = copy.copy(self._args) |
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430 | tmp._coef = copy.copy(self._coef) |
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431 | tmp._const = self._const |
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432 | return tmp |
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433 | |
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434 | def scale(self, val): |
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435 | for i in xrange(len(self._coef)): |
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436 | self._coef[i] *= val |
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437 | self._const *= val |
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438 | |
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439 | def negate(self): |
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440 | self.scale(-1) |
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441 | |
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442 | def pprint(self, ostream=None, nested=True, eol_flag=True): |
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443 | """Print this expression""" |
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444 | if ostream is None: |
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445 | ostream = sys.stdout |
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446 | if nested: |
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447 | print >>ostream, self.name + "(", |
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448 | first=True |
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449 | if self._const != 0: |
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450 | print >>ostream, str(self._const), |
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451 | first=False |
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452 | for i, arg in enumerate(self._args): |
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453 | if first==False: |
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454 | print >>ostream, ",", |
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455 | if self._coef[i] != 1: |
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456 | print >>ostream, str(self._coef[i])+" * ", |
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457 | if arg.is_expression(): |
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458 | arg.pprint(ostream=ostream, nested=nested, eol_flag=False) |
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459 | else: |
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460 | print >>ostream, str(arg), |
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461 | first=False |
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462 | print >>ostream, ")", |
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463 | if eol_flag==True: |
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464 | print >>ostream, "" |
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465 | |
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466 | def _apply_operation(self, values): |
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467 | """Evaluate the expression""" |
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468 | return sum(c*values.next() for c in self._coef) + self._const |
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469 | |
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470 | |
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471 | |
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472 | def generate_expression(*_args): |
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473 | def _clone_if_needed(obj): |
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474 | count = sys.getrefcount(obj) - generate_expression.UNREFERENCED_EXPR_COUNT |
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475 | if generate_expression.clone_if_needed_callback: |
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476 | generate_expression.clone_if_needed_callback(count) |
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477 | if count == 0: |
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478 | return obj |
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479 | elif count > 0: |
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480 | generate_expression.clone_counter += 1 |
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481 | return obj.clone() |
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482 | else: |
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483 | raise RuntimeError, "Expression entered generate_expression() " \ |
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484 | "with too few references (%s<0); this is indicative of a " \ |
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485 | "SERIOUS ERROR in the expression reuse detection scheme." \ |
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486 | % ( count, ) |
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487 | |
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488 | etype = _args[0] |
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489 | _self = _args[1] |
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490 | if _self.is_expression(): |
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491 | _self = _clone_if_needed(_self) |
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492 | elif _self.is_indexed(): |
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493 | raise ValueError, "Argument for expression '%s' is an n-ary "\ |
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494 | "numeric value: %s\n Have you given variable or "\ |
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495 | "parameter '%s' an index?" % (etype, _self.name, _self.name) |
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496 | |
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497 | # |
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498 | # First, handle the special cases of unary opertors |
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499 | # |
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500 | if etype == 'neg': |
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501 | if type(_self) is _SumExpression: |
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502 | _self.negate() |
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503 | return _self |
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504 | else: |
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505 | etype = 'rmul' |
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506 | other = NumericConstant(value=-1) |
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507 | elif etype == 'abs': |
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508 | return _AbsExpression([_self]) |
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509 | else: |
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510 | other = as_numeric(_args[2]) |
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511 | if other.is_expression(): |
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512 | other = _clone_if_needed(other) |
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513 | elif other.is_indexed(): |
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514 | raise ValueError, "Argument for expression '%s' is an n-ary "\ |
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515 | "numeric value: %s\n Have you given variable or "\ |
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516 | "parameter '%s' an index?" % (etype, _self.name, _self.name) |
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517 | |
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518 | # |
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519 | # Binary operators can either be "normal" or "reversed"; reverse all |
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520 | # "reversed" opertors |
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521 | # |
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522 | if etype[0] == 'r': |
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523 | # |
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524 | # This may seem obvious, but if we are performing an |
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525 | # "R"-operation (i.e. reverse operation), then simply reverse |
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526 | # self and other. This is legitimate as we are generating a |
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527 | # completely new expression here, and the _clone_if_needed logic |
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528 | # above will make sure that we don't accidentally clobber |
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529 | # someone else's expression (fragment). |
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530 | # |
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531 | tmp = _self |
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532 | _self = other |
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533 | other = tmp |
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534 | etype = etype[1:] |
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535 | |
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536 | # |
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537 | # Some binary operators are special cases of other operators |
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538 | # |
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539 | multiplier = 1 |
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540 | if etype == 'sub': |
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541 | multiplier = -1 |
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542 | etype = 'add' |
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543 | |
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544 | # |
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545 | # Now, handle all binary operators |
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546 | # |
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547 | if etype == 'add': |
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548 | # |
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549 | # self + other |
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550 | # |
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551 | self_type = type(_self) |
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552 | other_type = type(other) |
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553 | if self_type is _SumExpression: |
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554 | if other_type is NumericConstant: |
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555 | _self._const += multiplier * other() |
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556 | elif other_type is _ProductExpression \ |
---|
557 | and len(other._numerator) == 1 \ |
---|
558 | and not other._denominator: |
---|
559 | _self._args.append(other._numerator[0]) |
---|
560 | _self._coef.append(multiplier*other.coef) |
---|
561 | elif other_type is _SumExpression: |
---|
562 | if multiplier < 0: |
---|
563 | other.negate() |
---|
564 | _self._args.extend(other._args) |
---|
565 | _self._coef.extend(other._coef) |
---|
566 | _self._const += other._const |
---|
567 | else: |
---|
568 | _self._args.append(other) |
---|
569 | _self._coef.append(multiplier) |
---|
570 | ans = _self |
---|
571 | else: |
---|
572 | if other_type is _SumExpression: |
---|
573 | if multiplier < 0: |
---|
574 | other.negate() |
---|
575 | if self_type is NumericConstant: |
---|
576 | other._const += _self() |
---|
577 | elif self_type is _ProductExpression and \ |
---|
578 | len(_self._numerator) == 1 and \ |
---|
579 | not _self._denominator: |
---|
580 | other._args.append(_self._numerator[0]) |
---|
581 | other._coef.append(_self.coef) |
---|
582 | else: |
---|
583 | other._args.append(_self) |
---|
584 | other._coef.append(1) |
---|
585 | ans = other |
---|
586 | else: |
---|
587 | ans = _SumExpression() |
---|
588 | if self_type is NumericConstant: |
---|
589 | ans._const += _self() |
---|
590 | elif self_type is _ProductExpression and \ |
---|
591 | len(_self._numerator) == 1 and \ |
---|
592 | not _self._denominator: |
---|
593 | ans._args.append(_self._numerator[0]) |
---|
594 | ans._coef.append( _self.coef) |
---|
595 | else: |
---|
596 | ans._args.append(_self) |
---|
597 | ans._coef.append(1) |
---|
598 | if other_type is NumericConstant: |
---|
599 | ans._const += multiplier * other() |
---|
600 | elif other_type is _ProductExpression and \ |
---|
601 | len(other._numerator) == 1 and \ |
---|
602 | not other._denominator: |
---|
603 | ans._args.append(other._numerator[0]) |
---|
604 | ans._coef.append( multiplier*other.coef) |
---|
605 | else: |
---|
606 | ans._args.append(other) |
---|
607 | ans._coef.append( multiplier) |
---|
608 | |
---|
609 | # Special cases for simplifying expressions |
---|
610 | if ans._const == 0 and len(ans._args) == 1 and ans._coef[0] == 1: |
---|
611 | return ans._args[0] |
---|
612 | return ans |
---|
613 | |
---|
614 | elif etype == 'mul': |
---|
615 | # |
---|
616 | # self * other |
---|
617 | # |
---|
618 | self_type = type(_self) |
---|
619 | other_type = type(other) |
---|
620 | if self_type is _ProductExpression: |
---|
621 | if other_type is NumericConstant: |
---|
622 | _self.coef *= other() |
---|
623 | elif other_type is _ProductExpression: |
---|
624 | _self._numerator.extend(other._numerator) |
---|
625 | _self._denominator.extend(other._denominator) |
---|
626 | _self.coef *= other.coef |
---|
627 | else: |
---|
628 | _self._numerator.append(other) |
---|
629 | ans = _self |
---|
630 | else: |
---|
631 | if other_type is _ProductExpression: |
---|
632 | if self_type is NumericConstant: |
---|
633 | other.coef *= _self() |
---|
634 | else: |
---|
635 | other._numerator.append(_self) |
---|
636 | ans = other |
---|
637 | else: |
---|
638 | ans = _ProductExpression() |
---|
639 | if self_type is NumericConstant: |
---|
640 | ans.coef *= _self() |
---|
641 | else: |
---|
642 | ans._numerator.append(_self) |
---|
643 | if other_type is NumericConstant: |
---|
644 | ans.coef *= other() |
---|
645 | else: |
---|
646 | ans._numerator.append(other) |
---|
647 | |
---|
648 | # Special cases for simplifying expressions |
---|
649 | if ans.coef == 0: |
---|
650 | return NumericConstant(value=0) |
---|
651 | if ans.coef == 1 and len(ans._numerator) == 1 and not ans._denominator: |
---|
652 | return ans._numerator[0] |
---|
653 | return ans |
---|
654 | |
---|
655 | elif etype == 'div': |
---|
656 | # |
---|
657 | # self / other |
---|
658 | # |
---|
659 | self_type = type(_self) |
---|
660 | other_type = type(other) |
---|
661 | if self_type is _ProductExpression: |
---|
662 | if other_type is NumericConstant: |
---|
663 | _self.coef /= other() |
---|
664 | elif other_type is _ProductExpression: |
---|
665 | _self._numerator.extend(other._denominator) |
---|
666 | _self._denominator.extend(other._numerator) |
---|
667 | _self.coef /= other.coef |
---|
668 | else: |
---|
669 | _self._denominator.append(other) |
---|
670 | ans = _self |
---|
671 | else: |
---|
672 | if other_type is _ProductExpression: |
---|
673 | other.invert() |
---|
674 | if self_type is NumericConstant: |
---|
675 | other.coef *= _self() |
---|
676 | else: |
---|
677 | other._numerator.append(_self) |
---|
678 | ans = other |
---|
679 | else: |
---|
680 | ans = _ProductExpression() |
---|
681 | if self_type is NumericConstant: |
---|
682 | ans.coef *= _self() |
---|
683 | else: |
---|
684 | ans._numerator.append(_self) |
---|
685 | if other_type is NumericConstant: |
---|
686 | ans.coef /= other() |
---|
687 | else: |
---|
688 | ans._denominator.append(other) |
---|
689 | |
---|
690 | # Special cases for simplifying expressions |
---|
691 | if ans.coef == 0: |
---|
692 | return NumericConstant(value=0) |
---|
693 | if ans.coef == 1 and len(ans._numerator) == 1 and not ans._denominator: |
---|
694 | return ans._numerator[0] |
---|
695 | return ans |
---|
696 | |
---|
697 | elif etype == 'pow': |
---|
698 | # |
---|
699 | # self ** other |
---|
700 | # |
---|
701 | return _PowExpression((_self, other)) |
---|
702 | |
---|
703 | else: |
---|
704 | raise RuntimeError, "Unknown expression type '%s'" % etype |
---|
705 | |
---|
706 | ## |
---|
707 | ## "static" variables within the generate_expression function |
---|
708 | ## |
---|
709 | |
---|
710 | # [testing] clone_check_callback allows test functions to intercept the |
---|
711 | # call to _clone_if_needed and see the returned value from |
---|
712 | # sys.getrefcount. |
---|
713 | generate_expression.clone_if_needed_callback = None |
---|
714 | |
---|
715 | # [debugging] clone_counter is a count of the number of calls to |
---|
716 | # expr.clone() made during expression generation. |
---|
717 | generate_expression.clone_counter = 0 |
---|
718 | |
---|
719 | # [configuration] UNREFERENCED_EXPR_COUNT is a "magic number" that |
---|
720 | # indicates the stack depth between "normal" modeling and |
---|
721 | # _clone_if_needed(). If an expression enters _clone_if_needed() with |
---|
722 | # UNREFERENCED_EXPR_COUNT references, then there are no other variables |
---|
723 | # that hold a reference to the expression and cloning is not necessary. |
---|
724 | # If there are more references than UNREFERENCED_EXPR_COUNT, then we |
---|
725 | # must clone the expression before operating on it. It should be an |
---|
726 | # error to hit _clone_if_needed() with fewer than |
---|
727 | # UNREFERENCED_EXPR_COUNT references. |
---|
728 | generate_expression.UNREFERENCED_EXPR_COUNT = 10 |
---|
729 | |
---|
730 | |
---|
731 | ExpressionRegistration('<', _LessThanExpression) |
---|
732 | ExpressionRegistration('lt', _LessThanExpression) |
---|
733 | ExpressionRegistration('>', _LessThanExpression, True) |
---|
734 | ExpressionRegistration('gt', _LessThanExpression, True) |
---|
735 | ExpressionRegistration('<=', _LessThanOrEqualExpression) |
---|
736 | ExpressionRegistration('lte', _LessThanOrEqualExpression) |
---|
737 | ExpressionRegistration('>=', _LessThanOrEqualExpression, True) |
---|
738 | ExpressionRegistration('gte', _LessThanOrEqualExpression, True) |
---|
739 | ExpressionRegistration('=', _EqualToExpression) |
---|
740 | ExpressionRegistration('eq', _EqualToExpression) |
---|
741 | |
---|
742 | if False: |
---|
743 | ExpressionRegistration('+', _SumExpression) |
---|
744 | ExpressionRegistration('sum', _SumExpression) |
---|
745 | ExpressionRegistration('*', _ProductExpression) |
---|
746 | ExpressionRegistration('prod', _ProductExpression) |
---|
747 | #ExpressionRegistration('-', _MinusExpression) |
---|
748 | #ExpressionRegistration('minus', _MinusExpression) |
---|
749 | #ExpressionRegistration('/', _DivisionExpression) |
---|
750 | #ExpressionRegistration('divide', _DivisionExpression) |
---|
751 | #ExpressionRegistration('-', _NegateExpression) |
---|
752 | #ExpressionRegistration('negate', _NegateExpression) |
---|
753 | ExpressionRegistration('abs', _AbsExpression) |
---|
754 | ExpressionRegistration('pow', _PowExpression) |
---|
755 | |
---|