[Help-gsl] gsl_linalg_LU_decomp Function

[m . p . boulton]

I'm having some trouble with the gsl_linalg_LU_decomp function from the GSL 
library.

Basically I have a matrix called 'matrix' and a permutation matrix called
'indx', both of which are of length mat_size + 1 (except that 'matrix' is in 2D
of course so it has two columns of that length). However, GCC flags up an error
when I run the code saying:

gsl: lu.c:67: ERROR: permutation length must match matrix size

I have made a thorough check that both 'matrix' and 'indx' are of the same
length, because of course the matrix cannot be solved if they aren't. However
aside from this obvious check I'm stumped.

Does this error actually mean something else?

Kind Regards,

Matt