$ cat matmul.f90
program main
real, dimension(2,2) :: a
real, dimension(4,2) :: c
a = reshape((/ 1.0, 1.0, 0.0, 1.0/), shape(a))
c = 42.
c(1:2,1:2) = matmul(a, transpose(a))
print *,c(1:2,1:2)
print *,matmul(a, transpose(a))
print *,c(3:4,1:2)
end
$ gfortran matmul.f90
$ ./a.out
1.000000 1.000000 43.00000 44.00000
1.000000 1.000000 1.000000 2.000000
0.000000 0.000000 42.00000 42.00000
$ gfortran -v
Using built-in specs.
Target: i686-pc-linux-gnu
Configured with: ../gcc-4.1/configure --prefix=/home/ig25
--enable-languages=c,f95
Thread model: posix
gcc version 4.1.0 20050603 (experimental)
The problem is in the zeroing of the result, which assumes
a packed return array.
--
Summary: matmul does not deal with non-packed result
Product: gcc
Version: 4.1.0
Status: UNCONFIRMED
Keywords: wrong-code
Severity: normal
Priority: P2
Component: libfortran
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: tkoenig at gcc dot gnu dot org
CC: gcc-bugs at gcc dot gnu dot org
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21926
