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Foil 40 Computer Languages and Space - Time Properties

From Complex Systems and Parallel Computing CPSP713 Case studies in Computational Science -- Spring Semester 1996. by Geoffrey C. Fox
High Performance Fortran
    • Dimension A,B (10000)
    • A=A+B
Space (elements of arrays A,B) in problem is mapped into space (i.e. arrays preserved) in Virtual Problem
---> Compiler can recognize data parallelism
---> Good parallel performance on all machines
Fortran77 Do 1 I = 1, 10000
    • 1 A(I) = A(I) + B(I)
Space in problem is mapped into time (successive iterations of DO loop) in Virtual Problem
---> Compiler has to "undo" this to recognize parallelism and generally fails
---> Good languages preserve problem architecture

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