In some situations, you may need to perform a number of FFTs of the same dimension and lengths. For example, you may need to transform a number of one-dimensional data sets of the same length. To specify this number, use the DFTI_NUMBER_OF_TRANSFORMS parameter, which has the default value of 1. You can set this parameter to a positive integer value using the Integer data type in Fortran and MKL_LONG data type in C.
Note
The data sets to be transformed must not have common elements. Therefore one (or both) of the configuration parameters DFTI_INPUT_DISTANCE and DFTI_OUTPUT_DISTANCE is required if DFTI_NUMBER_OF_TRANSFORMS is greater than one.