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passing wrong type of agrument corrupts unrelated data
- From: Anton Shterenlikht <mexas at bristol dot ac dot uk>
- To: fortran at gcc dot gnu dot org
- Date: Thu, 28 Jul 2011 15:08:49 +0100
- Subject: passing wrong type of agrument corrupts unrelated data
I came across this accidentally.
Maybe I'm just overheating.
I'm calling a lapack routine
from my code, and after exit
from that lapack routine, an
unrelated array is corrupted.
This happens because I pass
it integer arrays instead of
double precision.
I know I should use interface block
to avoid this in the first place.
HOwever, I expected to get a segfault
in a situation like this.
$ cat z.f90
program z
implicit none
double precision :: c(6,6),comp(6,6)
INTEGER :: I,J,IPIV(6),INFO, WORK(6),CHECK(6,6)
C=0.0d0
FORALL(I=1:6) C(I,I)=1.0d0
FORALL(I=1:3) C(I,1:3) = C(I,1:3) + 2.0d0
COMP = C
WRITE(*,*) "Comp"
WRITE(*,'(6ES15.7)') (Comp(I,:), I=1,6)
! http://www.netlib.org/lapack/double/dgetrf.f
CALL DGETRF(6,6,COMP,6,IPIV,INFO)
WRITE(*,*) "C before dgetri"
WRITE(*,'(6ES15.7)') (C(I,:), I=1,6)
! http://www.netlib.org/lapack/double/dgetri.f
CALL DGETRI(6,COMP,6,IPIV,WORK,6,INFO)
WRITE(*,*) "C after dgetri"
WRITE(*,'(6ES15.7)') (C(I,:), I=1,6)
end program z
$ ./a.out
Comp
3.0000000E+00 2.0000000E+00 2.0000000E+00 0.0000000E+00 0.0000000E+00 0.0000000E+00
2.0000000E+00 3.0000000E+00 2.0000000E+00 0.0000000E+00 0.0000000E+00 0.0000000E+00
2.0000000E+00 2.0000000E+00 3.0000000E+00 0.0000000E+00 0.0000000E+00 0.0000000E+00
0.0000000E+00 0.0000000E+00 0.0000000E+00 1.0000000E+00 0.0000000E+00 0.0000000E+00
0.0000000E+00 0.0000000E+00 0.0000000E+00 0.0000000E+00 1.0000000E+00 0.0000000E+00
0.0000000E+00 0.0000000E+00 0.0000000E+00 0.0000000E+00 0.0000000E+00 1.0000000E+00
C before dgetri
3.0000000E+00 2.0000000E+00 2.0000000E+00 0.0000000E+00 0.0000000E+00 0.0000000E+00
2.0000000E+00 3.0000000E+00 2.0000000E+00 0.0000000E+00 0.0000000E+00 0.0000000E+00
2.0000000E+00 2.0000000E+00 3.0000000E+00 0.0000000E+00 0.0000000E+00 0.0000000E+00
0.0000000E+00 0.0000000E+00 0.0000000E+00 1.0000000E+00 0.0000000E+00 0.0000000E+00
0.0000000E+00 0.0000000E+00 0.0000000E+00 0.0000000E+00 1.0000000E+00 0.0000000E+00
0.0000000E+00 0.0000000E+00 0.0000000E+00 0.0000000E+00 0.0000000E+00 1.0000000E+00
C after dgetri
3.0000000E+00 2.0000000E+00 2.0000000E+00 0.0000000E+00 0.0000000E+00 7.1428571E-01
2.0000000E+00 3.0000000E+00 2.0000000E+00 0.0000000E+00 0.0000000E+00 -2.8571429E-01
2.0000000E+00 2.0000000E+00 3.0000000E+00 0.0000000E+00 0.0000000E+00 -2.8571429E-01
0.0000000E+00 0.0000000E+00 0.0000000E+00 1.0000000E+00 0.0000000E+00 0.0000000E+00
0.0000000E+00 0.0000000E+00 0.0000000E+00 0.0000000E+00 1.0000000E+00 0.0000000E+00
0.0000000E+00 0.0000000E+00 0.0000000E+00 0.0000000E+00 0.0000000E+00 0.0000000E+00
Note that 3 values of array C have
become corrupted after a call to
dgetri, even though array C is
not part of the arguments to this
routine.
This is with 4.1.2 20080704 on Linux 2.6.18-194.32.1.el5 #1 SMP x86_64
However, when I compile and link
the same code on my FreeBSD box:
FreeBSD 9.0-CURRENT #3 r221488 ia64
I get:
% gfortran45 -llapack -lblas z.f90
% ./a.out
Comp
3.0000000E+00 2.0000000E+00 2.0000000E+00 0.0000000E+00 0.0000000E+00 0.0000000E+00
2.0000000E+00 3.0000000E+00 2.0000000E+00 0.0000000E+00 0.0000000E+00 0.0000000E+00
2.0000000E+00 2.0000000E+00 3.0000000E+00 0.0000000E+00 0.0000000E+00 0.0000000E+00
0.0000000E+00 0.0000000E+00 0.0000000E+00 1.0000000E+00 0.0000000E+00 0.0000000E+00
0.0000000E+00 0.0000000E+00 0.0000000E+00 0.0000000E+00 1.0000000E+00 0.0000000E+00
0.0000000E+00 0.0000000E+00 0.0000000E+00 0.0000000E+00 0.0000000E+00 1.0000000E+00
C before dgetri
3.0000000E+00 2.0000000E+00 2.0000000E+00 0.0000000E+00 0.0000000E+00 0.0000000E+00
2.0000000E+00 3.0000000E+00 2.0000000E+00 0.0000000E+00 0.0000000E+00 0.0000000E+00
2.0000000E+00 2.0000000E+00 3.0000000E+00 0.0000000E+00 0.0000000E+00 0.0000000E+00
0.0000000E+00 0.0000000E+00 0.0000000E+00 1.0000000E+00 0.0000000E+00 0.0000000E+00
0.0000000E+00 0.0000000E+00 0.0000000E+00 0.0000000E+00 1.0000000E+00 0.0000000E+00
0.0000000E+00 0.0000000E+00 0.0000000E+00 0.0000000E+00 0.0000000E+00 1.0000000E+00
C after dgetri
3.0000000E+00 2.0000000E+00 2.0000000E+00 0.0000000E+00 0.0000000E+00 0.0000000E+00
2.0000000E+00 3.0000000E+00 2.0000000E+00 0.0000000E+00 0.0000000E+00 0.0000000E+00
2.0000000E+00 2.0000000E+00 3.0000000E+00 0.0000000E+00 0.0000000E+00 0.0000000E+00
0.0000000E+00 0.0000000E+00 0.0000000E+00 1.0000000E+00 0.0000000E+00 0.0000000E+00
0.0000000E+00 0.0000000E+00 0.0000000E+00 0.0000000E+00 1.0000000E+00 0.0000000E+00
0.0000000E+00 0.0000000E+00 0.0000000E+00 0.0000000E+00 0.0000000E+00 1.0000000E+00
in other words, here passing wrong type
arguments to dgerti didn't corrupt and
unrelated array C.
--
Anton Shterenlikht
Room 2.6, Queen's Building
Mech Eng Dept
Bristol University
University Walk, Bristol BS8 1TR, UK
Tel: +44 (0)117 331 5944
Fax: +44 (0)117 929 4423