Because 2838 + 494 = 3332, I believe PETSc calculates flops of an inner product as n-1, where n is the vector length.
On Fri, Dec 30, 2011 at 4:30 PM, Junchao Zhang <junchao.zhang at gmail.com>wrote: > Hello, > I have a sparse matrix A. Its size is 494 x 494. It has 1666 nonzeros. > I call MatMult(A, x, y). From the profiling result (got by > -log_summary), I find MatMult's flops is 2838. > I think the flops should be nnz x 2 = 1666 x 2 = 3332. I don't know how > PETSc got this number (2838). > I also observed the phenomena with other matrices. It seems PETSc always > give smaller flops. Why? > > Thank you! > -- Junchao Zhang > -- Junchao Zhang -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20111230/2a26b937/attachment.htm>
