Shot in the dark: Anyone ever use CLAPACK routines?

[Kevin D. Clark]

Bruce Labitt writes:

> Well, I have something to try...  If one actually RTFM or in this case 
> the readme, one finds the following:
> 
> # As a final point, we must stress that there is a difference in the definition
> # of a two-dimensional array in Fortran and C.

The difference that you cite here -- the difference between
column-major order versus row-major order -- is sort-of a well-known
difference between C and Fortran.  


[...]
> # Instead, you must use a one-dimensional C array of size LDA X N
> # double-words (or else malloc the same amount of space).
> # We recommend using the following code to get the array CLAPACK will be 
> # expecting:
> #
> #    double *A;
> #    A = malloc( LDA*N*sizeof(double) );
> 
> Umm, yeah, I can do that!  My original code had that...  For some reason I got rid of it.
> So a SEG FAULT makes some sense for my 9x9.  Because in C the array (matrix) does not have 
> to be contiguous in memory.  But FORTRAN is assuming a column major contiguous array.  So it
> seems likely I could access unallocated memory, and hence a seg fault.  

In my opinion, you would do very well to start with a *known working
example* from whatever matrix library you are working
with...paying special attention to the memory allocation parts....and
then try to transmogrify this into whatever you are trying to do with
this program.

--kevin
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