Add modern poisson2d solver & rename optimized.f90 #23
Commits on Jun 29, 2021
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feat: add modernized poisson2d solver
Refactorings ------------ 1. Use BLOCK for tighter variable scoping (reduces some clutter). 2. Use array statements with vector subscripts to write compact initializations. 3. Use DO CONCURRENT to express fine-grained parallelism and expose opportunities for optimizations such as vectorization, multithreading, or GPU offloading. 4. Replace some magic values, e.g., initial delta. 5. Eliminate some unnecessary computation by initializing and updating only values that actually need initializing and updating. 6. Use more compact conditional logic. 7. Use a real kind specificaiton based on precision requirements rather than the ambiguously defined double-precision representation of any one given compiler on any one given platform. 8. Eliminate unnecessary precision specifiers ("_dp") when an expression is simply a constant that is exactly representable in any reasonable floating-point representation. 9. Separate the procedure interface into a module and the procedure definition into a submodule.** 10. Use a more descriptive variable names in a few places. 11. Add comments! (includeing some in FORD style) ** In larger projects, item 9 makes code much more user-friendly by isolation the application programmer interface (API) and reduces compile times by eliminating unnecessary compilation cascades. -
rename optimized.f90 to archaic.f90
This code is old-fashioned, verbose, and most importantly, less clealry expressive, particularly in terms of exposing optimization opportunties, which makes the file name a misnomer. By contrast, commit a7ccf54 introduces a modern.f90 refactored to expose concurrency more explicitly through the use of `do concurrent` and array statements, both of which express sets of operations that can be safely executed in any order, opening up opportunities for vectorization, multithreading, and GPU offloading. In timings on a 2.3 GHz 8-Core Intel Core i9, modern.f90 executes in roughly the same time -- possibly 5-10% longer based on informal ad hoc testing -- but is considerably more compact in many places, is arguably more clear and expressive.
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Either is fine. I'm a minimalist so I use the first one because the `_dp` isn't required when the real literal is exactly representable in the chosen floating-post representation, which presumably is the case for `1.` in any floating-point scheme. Co-authored-by: Ondřej Čertík <[email protected]>
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I concur that `_dp` is required in this one. Co-authored-by: Ondřej Čertík <[email protected]>
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Co-authored-by: Ondřej Čertík <[email protected]>
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Co-authored-by: Milan Curcic <[email protected]>
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Co-authored-by: Ondřej Čertík <[email protected]>
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Co-authored-by: Milan Curcic <[email protected]>
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