mtimesx issue , Execution time

Hi,

I am trying run below code with mtimesx as below

 tic
      mtimesx('SPEEDOMP','OMP_SET_NUM_THREADS(4)');
      C=mtimesx(A,B);
      mtimesx
to

c

where, A= 1x3x79x 50000 complex 4D matrix, B=3x2x79 complex matrix, C= 1x2x79x50000 4D complex matrix.

I find that mtimesx is using SPEED mode instead of SPEEDOMP mode and execution time is about 0.3-0.4 ms .

I would like to know :

1. Why SPEEDOMP mode is not used.
2. Can the execution time be improved by SPEEDOMP mode.
3. Is there any other arlternative to improve the execution time.

I am using following setup

Matlab '9.6.0.1072779 (R2019a)'

Windows 7, 64 bit.

memory 8 GB,

Intel i7-4800MQ , 4Core, 8 Theread

Looking forward .

[Jayant chouragade]

OK , so I mtimesx suggest that to make SPEEDOMP mode to work , mtimesx should be compliled by OPENMP compiler. i.e MSVC or Intel Intel Parallel Studio XE . Free MinGW64 Compiler will complie mtimesx but does not support OPENMP.

I have installed MSVC 2019 . But still strugling to get it setup for matlab as matlab is not detecting the complier when using

mex -setup CPP -v ;

Below link discussed without conclusion.

https://in.mathworks.com/matlabcentral/answers/423781-microsoft-visual-studio-2017-is-not-detected-in-matlab-2018b

But even I acheive and get OPENMP complier will I get speed improvement by using SPEEDOMP over SPEED mode ?

best.

[James Tursa]

MTIMESX has not been updated in many years. In particular, it has not been updated for the R2018a+ interleaved complex memory model, and it has not been updated for various compilers OpenMP flags.

Getting it to compile with the OpenMP flags is probably just a matter of writing a short script. But even if this were done, the code would not operate as intended for the R2018a+ interleaved complex memory model. Instead, it would use copy-in and copy-out methods for complex variables, which would totally defeat the purpose. Simply compiling with the -R2018a option will not work.

Given that R2020b has a new PAGEMTIMES function that duplicates the functionality of MTIMESX, I doubt I will ever spend the time to update MTIMESX just to support versions R2018a-R2020a. It would take a lot of effort to get the interleaved complex functionality working just for these versions.