Developer Reference for Intel® oneAPI Math Kernel Library for C
DFTI_NUMBER_OF_TRANSFORMS
If you need to perform a large number of identical FFTs, you can do this in a single call to a DftiCompute* function with the value of the DFTI_NUMBER_OF_TRANSFORMS configuration parameter equal to the actual number of the transforms. The default value of this parameter is 1. You can set this parameter to a positive integer value of the MKL_LONG data type. When setting the number of transforms to a value greater than one, you also need to specify the distance between forward-domain or backward-domain data layout using DFTI_FWD_DISTANCE and DFTI_BWD_DISTANCE configuration parameter or both.
- The data sets to be transformed must not have common elements; the DFTI_FWD_DISTANCE and DFTI_BWD_DISTANCE must be set explicitly to ensure that all data sets for each transform are independent.
All the sets of data must be located within the same memory block.
To better understand usage of the DFTI_NUMBER_OF_TRANSFORMS configuration parameter, see this example in your Intel® oneAPI Math Kernel Library (oneMKL) directory:
./examples/dftc/source/config_number_of_transforms.c