Computes the forward FFT.

Syntax

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);

Input Parameters

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:

  • _inout to DFTI_INPLACE
  • _in to DFTI_NOT_INPLACE

Output Parameters

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:

  • _inout to DFTI_INPLACE
  • _out to DFTI_NOT_INPLACE

Include Files

  • mkl.h

Description

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.

Prototype

 
  MKL_LONG DftiComputeForward( DFTI_DESCRIPTOR_HANDLE, void*, ... ); 
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