[petsc-users] Origin of f2cblaslapack source code

[Barry Smith]

  The tool is /bin/maint/toclapack.sh and is applied to the Fortran BLAS/LAPACK source. Credits are at the top of the file. We don't run the script each time but run the script once and generate a tarball which is downloaded on request.

   The testing of the source code for quad precision amounts to running the PETSc/TAO/SLEPc test suite, so it is not as extensive as it could be and only tests the functionality that we use. It would be great if someone figured out how to do a comprehensive test suite.

   I love quad precision but the general numerical computing community doesn't seem to care much about it hence such tools are really underdeveloped. I don't know of other commonly used numerical packages besides PETSc/TAO/SLEPc that that advantage of the __float128 support in GNU.

   Barry

  The Netlib effort to generate C code from Fortran BLAS/LAPACK source is really a piss-poor effort.

> On Nov 11, 2014, at 6:00 PM, Dave May <dave.mayhem23 at gmail.com> wrote:
> 
> Hello,
> 
> A colleague of mine asked me about quad precision support in blas/lapack libraries. Naturally I said just use petsc... however he couldn't be convinced.
> 
> I thought that the f2cblaslapack source which petsc's configure downloaded and compiled would be identical to that found at Netlib. However, a quick inspection of both source codes reveals that this is not the case.
> 
> I asked Matt and he told me that he thought Satish generated the particular source which petsc is fetching when --download-f2cblaslapack is invoked. 
> 
> I was wondering 
> (i) how was the quad precision source actually generated and 
> (ii) how extensively tested is that source code when used for quad precision arithmetic?
> 
> 
> Cheers,
>   Dave