The forward transform and backward transform are each associated with a scale factor σ of its own having the default value of 1. You can specify the scale factors for each or both transform(s) using the two configuration parameters DFTI_FORWARD_SCALE and DFTI_BACKWARD_SCALE. For example, for a one-dimensional transform of length n, you can use the default scale of 1 for the forward transform and set the scale factor for the backward transform to be 1/n, thus making the backward transform the inverse of the forward transform.
Set the scale factor configuration parameter using a real floating-point data type of the same precision as the value for DFTI_PRECISION.
Note
For inquiry of the scale factor with the DftiGetValue function in C, the value must have the same floating-point precision as the descriptor.