ippiReduceBits_32f8u_C1R gives different results

[steffenroeber]

Hi,

the ippiReduceBits_32f8u_C1R gives me different results on different machines:

  Ipp32f input[] = { 0, 0.5, 0.75, 1 };
  Ipp8u output[4];
  Ipp8u buffer[4];
  ippiReduceBits_32f8u_C1R(input, 16, output, 4, { 4, 1 }, 0, ippDitherNone, 255, buffer);

On one machine result is 0, 127, 190, 255

On second machine result is 0, 127, 191, 255

Is this a known bug (IPP Version 9.0)?

Best regards

[Shaojuan_Z_Intel]

Hi Steffen,

Depending on different system, there could be some small epsilon difference. Here is an article discusses the possible difference https://software.intel.com/en-us/articles/getting-reproducible-results-with-intel-mkl. Let us know if you have further question. Thanks!

[steffenroeber]

Hi,

but in this case this is no small epsilon I think.

The used formula here is: 0.75*255 which is 191,25. So, how can 190 be a valid result?

Regards Steffem