search

reinh-bader / fgsl

Fortran interface to the GNU Scientific Library
https://doku.lrz.de/display/PUBLIC/FGSL+-+A+Fortran+interface+to+the+GNU+Scientific+Library
GNU General Public License v2.0
83 stars 23 forks source link

test fgsl_linalg_qrpt_lssolve2 in linalg fails #39

Open reinh-bader opened 4 months ago

reinh-bader commented 4 months ago

build with ifx causes one test in linalg (fgsl_linalg_qrpt_lssolve2:x) to fail

Intel(R) Fortran Compiler for applications running on Intel(R) 64, Version 2024.0.2 Build 20231213 OS: Ubuntu 20.04.6 LTS / executing under WSL 2

reinh-bader commented 1 month ago

Depending on compiler and platform, the solution vector oscillates between [ 2.,-1.,0.] and [1.,0.,1.]. Further investigation will be needed.

reinh-bader commented 1 month ago

Further observation: It is already the prior call to fgsl_linalg_qrpt_decomp with a rank-deficient argument a that produces divergent results. The test is commented out for now. Next step would be to reproduce this in C.