I’d like to build GNU Octave with 64 bit indices support, and I’m using their release candidate - version 6.0.90 - available from here.

I encountered an issue with blas implementations incompatibility. Octave has 3 dependencies besides blas itself, that require blas by themselves: `qrupdate`

, `arpack`

, `sundials`

and `suitesparse`

.

It seems that only with openblas, I’m able to get this from octave’s configure report:

```
64-bit array dims and indexing: yes
64-bit BLAS array dims and indexing: yes
```

When using reference blas and lapack implementations, I get:

```
64-bit array dims and indexing: yes
64-bit BLAS array dims and indexing: no
```

I learned, after discussing with upstream that a test failure I experienced was due to mismatched blas implementations used between octave and it’s dependencies’ blas. Hence I’m wondering if there’s a policy towards defaulting to the reference blas and lapack implementation, vs openblas, where the former doesn’t seem to have 64 bit indexing support by default:

```
$ nix eval -f. blas.isILP64
false
```

Maybe *this* is not intended? (I’m on x86_64).

Are there any licensing issues that make the reference blas implementation preferred over openblas?

My current status is this: I’m going to make `qrupdate`

use `openblas`

, like `octave`

itself, since octave is the only package that depends upon `qrupdate`

, but for `suitesparse`

, `arpack`

and `sundials`

I am less sure, currently I’m testing building all of them with openblas.

For suitesparse, upstream recommends *not* using openblas, and not even the reference implementation. They recommend using `mkl`

which is unfree. See GitHub - DrTimothyAldenDavis/SuiteSparse: The official SuiteSparse library: a suite of sparse matrix algorithms authored or co-authored by Tim Davis, Texas A&M University .

Regarding the licensing concern, it seems that the licenses of `suitesparse`

, `arpack`

and `sundials`

are compatible with that of OpenBLAS (OpenBLAS’ is bsd3), but I could be wrong.

@ttuegel is maintainer of `suitesparse`

and `arpack`

. @flokli & @idontgetoutmuch are maintainers of sundials which accidentally, I’d be glad to have their opinion on Add KLU support to sundials by GuillaumeDesforges · Pull Request #94930 · NixOS/nixpkgs · GitHub .

Regards.