# ReFFT

Advanced Analysis Library Only

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

## Purpose

| Note This function is obsolete.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

Calculates the Fast Fourier Transform (FFT) of a real input array.

ReFFT performs the operation in place and overwrites the input 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.

### Example

/* Generate an array with random numbers and calculate the Fast Fourier Transform. */
double x[256], y[256];
n;
n = 256;
Uniform (n, x);
ReFFT (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 FFT. On output, the real part of the FFT. This operation is performed in place, meaning the values in this array are overwritten.
arrayXImg | double-precision array | On input, the values are ignored. On output, the imaginary part of the 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.