topic Re: Re:problem with potrf_scratchpad_size call in Intel® oneAPI Math Kernel Library

problem with potrf_scratchpad_size call

tdot — Wed, 13 Dec 2023 21:09:06 GMT

The call in question is:

std::int64_t scratchSzF = oneapi::mkl::lapack::potrf_scratchpad_size<std::complex<double>>(_queue, oneapi::mkl::uplo::upper, nnn, nnn);

In order to run without getting an invalid exception when called the 'lda' value must be= or greater than the matrix order value 'n'. In the example above the arguments are 'nnn'.

With 'nnn' value of 100 the call is satisfied and scratchSzF value of 0 is returned.

So;

- Why does 'lda' have to be equal matrix size 'n'? In fact 'lda' it can be greater than 'n'!?

- More importantly the return value of 0?

Running on Linux5.4.17 x86_64
mkl installed version is 2023.0.0

Re:problem with potrf_scratchpad_size call

VarshaS_Intel — Mon, 18 Dec 2023 17:23:59 GMT

Hi,

Thanks for posting in Intel Communities.

>>In the example above the arguments are 'nnn'.

Could you please provide us with the example you are referring to?

And also, could you please elaborate on your issue?

Thanks & Regards,

Varsha

Re: Re:problem with potrf_scratchpad_size call

tdot — Tue, 19 Dec 2023 22:03:03 GMT

Referring to the call found at potrf_scratchpad_size (intel.com).

scratchPadSize = oneapi::mkl::lapack::potrf_scratchpad_size<std::complex<double>>(_queue, oneapi::mkl::uplo::upper, n, lda);

If the value provided for lda is < the value provided for n an exception is thrown identifying the lda as the bad argument. If the value for lda is equal to or greater than the value for n no exception is thrown however the scratchPadSize retuned is 0. In my code the value for n and lda is set to 100 to avoid the exception. The 100 value represents a 10x10 complex data matrix.

My questions are;

Is it true/correct that lda >= n?
When given values to avoid the exception is a return of 0 correct?

Related to this issue, and to be posted separately. This is the first 4 successive calls to MKL LAPACK routines.

potrf_scratchpad_size
potrf - need above to work since it uses the calculated size. If I give it a value > 100 an exception is thrown on the value provided
potri _scratchpad_size - this exhibits the same problem.
potri

cheers

Re:problem with potrf_scratchpad_size call

VarshaS_Intel — Thu, 28 Dec 2023 08:45:29 GMT

Hi,

We are working on your issue internally, we will get back to you soon.

Thanks & Regards,

Varsha