Re: TRANSPOSE and MATMUL interaction

Peter wrote:
I am confused by the unexpected results from the following:

SUBROUTINE JacobianFwdDiff(m,n,fjac,ldfjac)

IMPLICIT NONE

INTEGER, INTENT(IN) :: m,n,ldfjac
REAL(8), DIMENSION(ldfjac,n), INTENT(OUT) :: fjac
REAL(8), DIMENSION(n,n) :: term1,M3,M4
REAL(8), DIMENSION(n,m) :: M1
REAL(8), DIMENSION(m,n) :: M2

! Code which computes fjac(1:m,1:n)

M1=TRANSPOSE(fjac(1:m,1:n)); M2=fjac(1:m,1:n)
M3=MATMUL(M1, M2); M4=MATMUL(M1(1:n,1:m), M2(1:m,1:n))
term1(1:n,1:n)=MATMUL(TRANSPOSE(fjac(1:m,1:n)), fjac(1:m,1:n))

Specifically, when m=ldfjac=769, n=1, the values for M3 and M4 are
identical, as I expected, but the value for term1 differs from these.
I thought the computation of term1 should be the same as that of M4,
but it is not.

What have I got wrong here?

What platform and compiler are you using? How are the results different? You wouldn't be doing this on an AIX machine with xlf by any chance, would you?

cheers,

paulv

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