SPM_matrix_times_vector_Version
version for the matrix-times-vector operations for sparse linear systems
version 1: -> automatically switch to version 2
version 2: classical loop over all matrix lines: do i = 1,nMatrixLines)
version 3: vectorize the loop over all matrix lines: do i = 1,nMatrixLines,i4 :: MxV(i:i+i4-1) = sum{ (MMM(i:i+i4-1,.) * X(.) } assuming that the intrinsic sum() function of INTEL-fortran is also perfectly vectorized.
Default:
SPM_matrix_times_vector_Version = 1