OT: Language for the ages

Gordon JC Pearce wrote: Ok, you asked for it... 1) There is an inertia factor, of course, with all those superb routine libraries in FORTRAN (LAPACK, SCALAPACK and all that stuff at the legendary netlib) 2) FORTRAN has been optimized for many decades to do just one kind of task: computations involving arrays of floats, with a very specific fetch/multiply/add to accumulator/increment pointers sequence. This is a very regular task and the optimizations in FORTRAN are directed to do this very efficiently. C compiler optimizers must address many other possibilities (C is a much more "general purpose" language). Thus, like it or not, for numeric computations involving matrix/vector float operations, FORTRAN is usually slightly faster than C. Of course, if you program a fast Fourier transform in FORTRAN, it might actually be slower because some of the operations don't fit the structure described above: you have to negate bits in pointers to form the "butterflies" (the basic FFT block). Why, even the storage scheme in FORTRAN reflects numerics-specific thinking: 2D matrices are stored column-wise, an appropriate choice if you know that en numerics, matrix/vector multiplication is best thought of as a weighted sum of the columns of the matrix, with the weights being the elements of the vector. C, being designed by non-numerics people, stores numbers row-wise. If you program numerics in C, you must always store matrices transposed to get around this fact. So, short explanation: FORTRAN is faster for array numerics, which forms the core of scientific numeric computing, simply because that's what the optimizer expects to find. C, having a more general purpose, considers many other possibilities and is less "tuned" to the needs of numerics. Carlos. Carlos E. Murillo-Sanchez email: carlos_murillo at ieee.org Dean of Engineering, Universidad Autonoma de Manizales, Manizales, Colombia ---- "Western civilization... thought like the greek, organized itself like the romans and believed in itself like the hebrew." -- Ortega y Gasset.