Bug report: out-of-bounds in ILADLC, ILADLR, ILAZLC, ILAZLR

[mat_cross]

In these four routines the 'quick return' logical test, e.g.

Code: Select all

IF( N.EQ.0 .OR. A(1, N).NE.ZERO .OR. A(M, N).NE.ZERO )

in ILADLC, needs to be split into two:

Code: Select all

IF( N.EQ.0 )

and

Code: Select all

IF( A(1, N).NE.ZERO .OR. A(M, N).NE.ZERO )

since logical expressions can be evaluated in any order in Fortran.

[Julien Langou]

Hi Mathew,

You are entirely right, the LAPACK codes were not correct, we corrected this in 3.2.1. (See: http://www.netlib.org/lapack/lapack-3.2.1.html, bug 002, svn r610 and svn r614).

Cheers,
Julien.

[jteg68]

Hi,

two comments:
shouldn't the test for N=0 be N<=0 instead?
shouldn't the code indicate an error in case N<=0? Now it returns the index of the last row/column and any buggy calling code will happily chug along instead of aborting.

/Jörgen

[Julien Langou]

Thanks for the comment. These subroutines (ILACLC,ILACLR, ILADLC,ILADLR,ILASLC,ILASLR,ILAZLC and ILAZLR) are LAPACK auxiliary subroutines. Therefore, as LAPACK auxiliary subroutines, they do not have any check on their arguments. For ILADLC, (( M>=0 ) .AND. ( N >= 0 ) .AND. ( LDA >= MAX( 1, N) ) ) is required for the subroutine to work properly but we do not check it. Julien.

[mat_cross]

Thanks guys: sorry for the duplicate. I picked up my source from http://www.netlib.org/lapack/lapack-3.2/SRC/ilazlc.f (via Google) and wrongly assumed that was the latest version.
I also see from the Google search that the third hit is the original discussion about the bug from a few years ago!