# ReInvFFT

Advanced Analysis Library Only

AnalysisLibErrType ReInvFFT (double arrayXReal[], double arrayXImg[], int numberOfElements);

## Purpose

| Note This function is obsolete. National Instruments recommends that you use InvFFTEx instead.

Calculates the inverse Fast Fourier Transform (FFT) of a complex sequence that results in a real output array.

Performing an FFT on a real array yields a complex result. The imaginary component array must be at least as large as the real component array.

ReInvFFT performs the operation in place and overwrites the input array. arrayXImg remains unchanged.

### Example

/* Generate an array with random numbers and calculate its real inverse Fast Fourier Transform. */
double x[256], y[256];
int n;
n = 256;
Uniform (n, 17, x);
Uniform (n, 17, y);
ReInvFFT (x, y, n);

## Parameters

Input
Name | Type | Description
numberOfElements | integer | Number of elements in the input arrays.
Output
Name | Type | Description
arrayXReal | double-precision array | On input, the real part of the array used to compute the inverse FFT. On output, the real part of the inverse FFT. This operation is performed in place, meaning the values in this array are overwritten.
arrayXImg | double-precision array | On input, the imaginary part to transform. On output, the imaginary part of the inverse FFT. This operation is performed in place, meaning the values in this array are overwritten.

## Return Value

Name | Type | Description
status | AnalysisLibErrType | A value that specifies the type of error that occurred. Refer to analysis.h for definitions of these constants.