LAPACK: Unable to determine CPU type, on Ubuntu and engineering sample CPU.

Hello everyone,

I am running MATLAB 2022b on Ubuntu 22.04. The CPUs used are Intel xeon 6148, engineering samples (which means these CPUs are just for test and not for sale, but they should be very close to the final official product). I found that this computer works perfectly on MATLAB 2020b and all other softwares, but runs into error on 2022b. The errors codes are as follows.

Input:

eig([1,0;0,1])

I got the following errors:

LAPACK: Unable to determine CPU type
Error using eig
LAPACK loading error:
No valid linear algebra library found for this architecture. lapack.spec is defective or the used architecture is not supported by MATLAB on this machine.

I suspect this is because I am using unofficial CPUs (engineering samples), but they works well on MATLAB 2020b. I wonder if it is possible to solve this problem and how. Thanks in advance!

Sincerely,

Chin Kung

[Heiko Weichelt]

Before using the fix I posted, could you please set the ENVs

BLAS_VERBOSITY=1

LAPACK_VERBOSITY=1

and report back the output you see, when running the same steps as in your original post.

Thanks.

[G]

Dear Heiko,

Thanks again for your suggestions!

I have tried to set these ENVs as you suggested here (BLAS_VERBOSITY=...), it seems they do not solve the problem (the output error is almost the same as the error above). However, setting ENVs such as BLAS_VERSION=... does solve the problem.

Sincerely,

C. K.

Answer 1

[Heiko Weichelt]

Please try to set the following ENVs before starting MATLAB:

BLAS_VERSION=mkl.so

LAPACK_VERSION=mkl.so

The mechanism to load BLAS/LAPACK, which uses MKL by default on x86_64, probably can't recognize this processor, and hence, errors out. We had to modify this behavior recently as customers experience weird issues for unsupported architectures.

Using the ENVs above forces MATLAB to load MKL without further checks.

[G]

Dear Heiko,

Thanks very much for your suggestions, it works on my computer!

Note:

A minor issue is that, the first time I execute something, an erroer message occurs, but the output is OK.

>> eig([1,0;0,1])
LAPACK: Unable to determine CPU type
LAPACK: trying environment LAPACK_VERSION...
LAPACK: loading mkl.so
LAPACK: loaded mkl.so@0x1469606375c0

ans =

     1
     1
     
>> eig([1,0;0,1])

ans =

     1
     1

Sincerely,

C. K.

[Heiko Weichelt]

Great. FYI, this is not error message you're seeing but a debug output. In earlier release they were only shown if you set the *_VERBOSITY ENVs but since 22b, we always show it if non-default BLAS or LAPACK libs are selected such that the user gets notified ENVs are used.