use strict;
use warnings;
use feature 'say';
use Alien::GSL;
use Math::GSL;
use Math::GSL::SparseMatrix ':all';

my $m = gsl_spmatrix_alloc( 1, 1 );

my $v;

#$v = 3 + (1 << 32); # no problem with this value
#$v = 2 + (1 << 32); # no problem with this value
#$v = 0 + (1 << 32); # no problem with this value
$v = 1 + (1 << 32); # blows up, but only if
                    # gsl_spmatrix_get($m, $v, 0)
                    # is called. 

die if gsl_spmatrix_set( $m, 1, 0, 1.5 );
say gsl_spmatrix_get($m, 1, 0);
say gsl_spmatrix_nnz( $m );
die if gsl_spmatrix_set( $m, $v, 0, 1.75 );
say gsl_spmatrix_get($m, $v, 0); # comment out to avoid blow up
                                  # when $v is 1 + (1 << 32).
                                  # But still gives wrong result
                                  # (for that value only).
say gsl_spmatrix_nnz( $m );
[download]

... something for tomorrow.

It's apparently a problem with the gsl library:

/*
This file: gsl_spmatrix.c
Modify the following "-I..." and "-L..." arguments accordingly.

Using the gsl-2.6 library that ships with Strawberry Perl 5.32.1-PDL, 
+build with:
gcc -o gsl_spmatrix.exe gsl_spmatrix.c -ID:/sp/_64/sp-5.32.1-PDL/c/inc
+lude -LD:/sp/_64/sp-5.32.1-PDL/c/lib -lgsl -lgslcblas -lm

Then execute gsl_spmatrix.exe

Using the gsl-2.7.1 library provided by Alien, build with:
gcc -o gsl_spmatrix.exe gsl_spmatrix.c -ID:/sp/_64/sp-5.32.1/perl/site
+/lib/auto/share/dist/Alien-GSL/include -LD:/sp/_64/sp-5.32.1/perl/sit
+e/lib/auto/share/dist/Alien-GSL/lib -lgsl -lgslcblas -lm

Then execute gsl_spmatrix.exe
*/
#include <stdio.h>
#include <stdlib.h>
#include <gsl/gsl_spmatrix.h>

int main(void) {
 size_t v = 1;
 v <<= 32;
 v += 1;
 printf("size of size_t is %d bytes\n", sizeof(size_t));
 gsl_spmatrix *m = gsl_spmatrix_alloc(1,1);
 gsl_spmatrix_set( m, 1, 0, 1.5 );
 printf("1: got: %f\n", gsl_spmatrix_get( m, 1, 0));
 printf("1: nnz: %d\n", gsl_spmatrix_nnz( m ));
 gsl_spmatrix_set( m, v, 0, 1.75 );
 if (v >= m->size1) printf("will be reported as 'out of range'\n");
 printf("2: got: %f\n", gsl_spmatrix_get( m, v, 0 ));
 printf("2: nnz: %d\n", gsl_spmatrix_nnz( m ));
 return 0;
}


/*
As is, the built executable outputs (for both gsl-2.6 and gsl-2.7.1):

D:\C>gsl_spmatrix.exe
size of _size_t is 8 bytes
1: got: 1.500000
1: nnz: 1
will be reported as 'out of range'
gsl: getset_source.c:27: ERROR: first index out of range
Default GSL error handler invoked.

But if the line "v += 1;" is changed to "v += 2" or to "v += 3" or to 
+"v += 0" then the output is:

D:\C>gsl_spmatrix.exe
size of _size_t is 8 bytes
1: got: 1.500000
1: nnz: 1
2: got: 1.750000
2: nnz: 2
*/
[download]

I haven't yet reached an understanding of the problem.
I think it should be reported to the gsl developers unless that has already been done.

Cheers,
Rob

Did you compile it from shell, created with portableshell.bat of Strawberry Perl 5.32.1-PDL? If I'm not using this shell, then gsl_spmatrix.exe complains it can't find libgsl-25__.dll, which would be in PATH created with portableshell.bat. I'm confused about this "25", does it mean anything? Should it be "26", i.e. is it "clean and correct" GSL 2.6 which ships with PDL-SP?

Using "gsl-2.7.1 library provided by Alien", there's no such complaint. I can only add, that "v += 1;" is not special. If 1st setter sets at index 2, then "v += 2;" leads to "out of range". They both set the same element. If two setters set different values, and 1st getter gets value after that, then it retrieves value set by 2nd setter. 1st value was overwritten.

I haven't reported yet, would it be better to write to both GSL and Math::GSL queues? (Math::GSL ignores whatever Alien::GSL has built) Or reporting to Math::GSL is enough, they'll see further?