FasTram: Methods and Capabilities
FasTram is a Fourier space based, matrix free Newton's method code (see Sears and Frink, J. Comp. Phys., 2003). Specifically it performs matrix vector multiplies as the matrix entries are formed. Thus a matrix is never stored. The memory requirements of this approach are significantly less than the approach applied in Tramonto. In addition, application of fast Fourier transforms to the convolutions allows for improved computational scaling. Combined these efficiencies may allow for performance enhancements that allow 3-dimensional DFT calculations on modest (even serial) computational platforms. The price to be paid for these efficiencies is loss of access to the matrix for preconditioning purposes. We have not yet fully assessed the impact of this limitation on a broad range of physical problems.
The FasTram code has not been approved for public release and is not available for download. Physical models implemented in the FasTram code included:
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