# InvFHT

Advanced Analysis Library Only

AnalysisLibErrType InvFHT (double array[], int numberOfElements);

## Purpose

Calculates the inverse Fast Hartley Transform (FHT) using the following formula:

where | Xi is the point of the inverse FHT
| and cas(x) = cos(x) + sin(x)

InvFHT performs the operation in place and overwrites the input array.

### Example

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

## Parameters

Input
Name | Type | Description
numberOfElements | integer | Number of elements in the input array. Default Value: 1024 Valid Values: Powers of 2.
Output
Name | Type | Description
array | double-precision array | On input, the array used to compute the inverse FHT. On output, the inverse FHT. 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.