Re: What does "Singular matrix in routine LUDCMP" mean?

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Michael Jones (mtj++at++babar)
Thu, 27 Apr 1995 07:15:03 -0700

On Apr 27, 1:39pm, Robert Webb wrote:
> Subject: What does "Singular matrix in routine LUDCMP" mean?
:
:When I run my Performer application, I sometimes get the message:
:
:"Singular matrix in routine LUDCMP"
:
:There is no mention of LUDCMP in any gl documentation I can find. It
:probably just means I've got a matrix of all zeros on the stack or
:something, but could someone clear this up for sure. Any pointers on why
:this might be happening (sometimes) would also be ace.

Good point. The warning was not sufficiently specific. This warning
is from the "Lower-Upper-Decomposition" routine that's part of
IRIS Performer's pfInvertMat() function. Not all matrices can be
inverted, just as the scalar zero has no multiplicative inverse. In the
case of matrices, it's those with one or more zeroes on the main
diagonal. When we try to invert such a matrix, the function
pfLUDecompMat() prints the warning and returns a failure notice
to pfInvertMat(), which returns a failure notice in turn.

:Has anyone else had this problem?

Ever since Sir William Rowan Hamilton developed the notion of
matrices, people worldwide have had this problem. ;-)

-- 


Be seeing you,      Phone:415.390.1455  Fax:415.965.2658 M/S:8U-590
Michael T. Jones    Silicon Graphics, Advanced Graphics Division
mtj++at++sgi.com         2011 N. Shoreline Blvd., Mtn. View, CA 94039-7311

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