Intel® oneAPI Math Kernel Library Developer Reference - C
Computes the forward FFT.
status = DftiComputeForward(desc_handle, x_inout);
status = DftiComputeForward(desc_handle, x_in, y_out);
status = DftiComputeForward(desc_handle, xre_inout, xim_inout);
status = DftiComputeForward(desc_handle, xre_in, xim_in, yre_out, yim_out);
Name |
Type |
Description |
|---|---|---|
desc_handle |
DFTI_DESCRIPTOR_HANDLE |
FFT descriptor. |
x_inout, x_in |
Array of type float or double depending on the precision of the transform, specified in the DFTI_PRECISION configuration setting. |
Data to be transformed in case of a real forward domain, specified in the DFTI_FORWARD_DOMAIN configuration setting. |
xre_inout, xim_inout, xre_in, xim_in |
Array of type float or double depending on the precision of the transform. |
Real and imaginary parts of the data to be transformed in the case of a complex forward domain, specified in the DFTI_FORWARD_DOMAIN configuration setting. |
The suffix in parameter names corresponds to the value of the configuration parameter DFTI_PLACEMENT as follows:
Name |
Type |
Description |
|---|---|---|
y_out |
Array of type float or double depending on the precision of the transform. |
The transformed data in case of a real backward domain, determined by the DFTI_FORWARD_DOMAIN configuration setting. |
xre_inout, xim_inout, yre_out, yim_out |
Array of type float or double depending on the precision of the transform. |
Real and imaginary parts of the transformed data in the case of a complex backward domain, determined by the DFTI_FORWARD_DOMAIN configuration setting. |
status |
MKL_LONG |
Function completion status. |
The suffix in parameter names corresponds to the value of the configuration parameter DFTI_PLACEMENT as follows:
The DftiComputeForward function accepts the descriptor handle parameter and one or more data parameters. Given a successfully configured and committed descriptor, this function computes the forward FFT, that is, the transform with the minus sign in the exponent, δ = -1.
The DFTI_COMPLEX_STORAGE, DFTI_REAL_STORAGE, and DFTI_CONJUGATE_EVEN_STORAGE configuration parameters define the layout of the input and output data and must be properly set in a call to the DftiSetValue function.
The FFT descriptor must be properly configured prior to the function call. Function calls needed to configure an FFT descriptor for a particular call to an FFT computation function are summarized in Configuring and Computing an FFT in C C++.
The number and types of the data parameters that the function requires may vary depending on the configuration of the descriptor. This variation is accommodated by variable parameters.
The function returns zero when it completes successfully. See Status Checking Functions for more information on the returned status.
MKL_LONG DftiComputeForward( DFTI_DESCRIPTOR_HANDLE, void*, ... );