Package: libblas3gf
Version: 1.2.20110419-5
Severity: important
Dear Maintainer,
The routine DGEMV (with TRANS = 'N') is supposed to perform the
operation
y ← beta * y + alpha * A * x
where the matrix A has dimensions M×N. In particular, if N=0 (and M >
0), A * x is the null vector (all elements are given by sums on an
empty set of indices). Consequently, if N = 0, the operation should
be
y ← beta * y
and NOT leave y untouched. For your convenience, I have attached a
program demonstrating the latter (wrong) behavior.
-- System Information:
Debian Release: wheezy/sid
APT prefers testing
APT policy: (900, 'testing'), (400, 'unstable'), (300, 'stable'), (100,
'experimental')
Architecture: amd64 (x86_64)
Foreign Architectures: i386
Kernel: Linux 3.6.6 (SMP w/8 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8) (ignored: LC_ALL
set to en_US.UTF-8)
Shell: /bin/sh linked to /bin/dash
Versions of packages libblas3gf depends on:
ii libblas3 1.2.20110419-5
libblas3gf recommends no packages.
libblas3gf suggests no packages.
-- no debconf information
Program test_gemv
Implicit none
Real*8 A(2,2)
Real*8 X(2), Y(2), beta
A(1,1) = 1.
A(1,2) = 1.
A(2,1) = 1.
A(2,2) = 1.
Y(1) = 1.
Y(2) = 2.
beta = 2.
c Should perform: Y <- beta * Y (empty sums in the matrix product)
call DGEMV('N', 2, 0, 0., A, 2, X, 1, beta, Y, 1)
write(*,*) Y(1)
write(*,*) Y(2)
end
c$$$Local Variables:
c$$$compile-command: "gfortran -o test_gemv test_gemv.f -lblas"
c$$$End:
