Convolve

Advanced Analysis Library Only

AnalysisLibErrType Convolve (double YArray[], int numberYElements, double XArray[], int numberXElements, double HArray[]);

Purpose

Finds the convolution of the input arrays. Convolve obtains the convolution using the following formula:

where	a = 0, b = i for 0 i < m
	a = i — m + 1, b = i for m i < n
	a = i — m + 1, b = n — 1 for n i n + m — 1

Note This formula description assumes that m

n. For m > n, exchange (x, y) and (m, n) in the previous equations.

Note This function temporarily allocates memory for use as a work area. If Convolve cannot allocate memory, the function returns an error code.

Example

/* Generate two arrays with random numbers and find their convolution. */
double x[256], y[256], cxy[512];
int n, m;
n = 256;
m = 256;
Uniform (n, 17, x);
Uniform (m, 17, y);
Convolve (x, n, y, m, cxy);

Parameters

Input
Name	Type	Description
YArray	double-precision array	First input array.
numberYElements	integer	Number of elements in YArray.
XArray	double-precision array	Second input array.
numberXElements	integer	Number of elements in XArray. numberXElements must be less than or equal to numberYElements.
Output
Name	Type	Description
HArray	double-precision array	Convolution array. The size of this array must be at least (numberYElements — numberXElements + 1) elements long. This algorithm executes more efficiently if the sizes of the input arrays are a power of two.

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.