------- Comment #10 from dfranke at gcc dot gnu dot org 2010-05-06 10:00 ------- (In reply to comment #9) > It looks like cubic time in N.
http://en.wikipedia.org/wiki/Matrix_multiplication#Algorithms_for_efficient_matrix_multiplication: "The running time of square matrix multiplication, if carried out naively, is O(n^3). The running time for multiplying rectangular matrices (one m x p-matrix with one p x n-matrix) is O(mnp)" Better algorithms than the one implemented exist. > > unconditionally returning NULL in MATMUL: ... > > I cannot reproduce that, am I correct to understand that you used some patched > gfortran? Index: simplify.c =================================================================== --- simplify.c (revision 159089) +++ simplify.c (working copy) @@ -3294,6 +3294,8 @@ gfc_simplify_matmul (gfc_expr *matrix_a, int row, result_rows, col, result_columns; int stride_a, offset_a, stride_b, offset_b; + return NULL; + if (!is_constant_array_expr (matrix_a) || !is_constant_array_expr (matrix_b)) return NULL; > Apparently, all the intrinsics should be audited for this kind of problem. Transformational intrinsics that return an arrays, to begin with. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43996
