Calculate the FFT from Vec elements [VecIndex]..[VecIndex+Len-1] and store the results in the calling object elements [Index]..[Index+Len-1]. The Len parameter must be a power of two. Size and Complex properties of the calling object must be set explicitly. An exception is raised if ConditionCheck is True and array borders are overrun. If Vec is complex, then complex to complex forward FFT is performed. If Vec is real, then real to complex forward FFT is performed. 

Note This is the indexed version of the FFT routine . Look there for more information on FFT parameters and storage requirements.

FFT Method