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Hi all,
This is a question on f2py. I am using a Crank Nicholson scheme to model a diffusion process and in the quest of some extra speed I started playing with f2py. However I do not seem to be able to get any significant boost in the performance of the code. In the following simple example I am building a tridiagonal array with plain python for loops and by calling a simple fortran subroutine that does the same thing. Here goes the python script: import numpy as np import time import learnf90_05 import sys run = sys.argv[1] try: dim = np.float(sys.argv[2]) except: dim = 500 elem = np.ones(dim) ### Python routine if run == "Python": t_python_i = time.time() array_python = np.zeros((dim, dim)) for row in np.arange(1,dim-1): array_python[row, row-1] = elem[row] array_python[row, row] = elem[row] array_python[row,row+1] = elem[row] t_python_f = time.time() python_time = t_python_f - t_python_i print("Python time: %0.5e" %(python_time)) ###fortran routine elif run == "Fortran": t_fortran_i = time.time() fortran_array = learnf90_05.test(j = dim, element = elem) t_fortran_f = time.time() fortran_time = t_fortran_f - t_fortran_i print("Fortran time: %0.5e" %(fortran_time)) And the fortran subroutine called test is here: subroutine test(j, element, a) integer, intent(in) :: j integer :: row, col real(kind = 8), intent(in) :: element(j) real(kind = 8), intent(out) :: a(j,j) do row=2,j-1 a(row,row-1) = element(row) a(row, row) = element(row) a(row, row+1) = element(row) enddo end The subroutine is compiled with Gfortran 4.2 on Osx 10.5.8. Running the python script with array sizes 300x300 and 3000x3000 gives for the python plain for loops: dhcp103:learnf vasilis$ python fill_array.py Python 3000 Python time: 1.56063e-01 dhcp103:learnf vasilis$ python fill_array.py Python 300 Python time: 4.82297e-03 and for the fortran subroutine: dhcp103:learnf vasilis$ python fill_array.py Fortran 3000 Fortran time: 1.16298e-01 dhcp103:learnf vasilis$ python fill_array.py Fortran 300 Fortran time: 8.83102e-04 It looks like the gain in performance is rather low compared to tests i have seen elsewhere. Am I missing something here..? Cheers...Vasilis --
------------------------------------------------ Vasileios Gkinis PhD student Center for Ice and Climate Niels Bohr Institute Juliane Maries Vej 30 2100 Copenhagen Denmark
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------------------------------------------------ Vasileios Gkinis PhD student Center for Ice and Climate Niels Bohr Institute Juliane Maries Vej 30 2100 Copenhagen Denmark
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