Documentation

mexihat

Mexican hat wavelet

Syntax

[PSI,X] = mexihat(LB,UB,N)

Description

[PSI,X] = mexihat(LB,UB,N) returns values of the Mexican hat wavelet on an N point regular grid, X, in the interval [LB,UB].

Output arguments are the wavelet function PSI computed on the grid X.

This wavelet has [-5 5] as effective support. Although [-5 5] is the correct theoretical effective support, a wider effective support, [-8 8], is used in the computation to provide more accurate results.

This function is proportional to the second derivative function of the Gaussian probability density function.

    Note:   You can use gauswavf to obtain a second order derivative of a Gaussian wavelet. If you use the negative of this normalized derivative, the resulting wavelet resembles the Mexican hat wavelet.

Examples

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Mexican Hat Wavelet

Create a Mexican hat wavelet with support on [-5,5]. Use 1,000 sample points. Plot the result.

lb = -5;
ub = 5;
N = 1000;
[psi,xval] = mexihat(lb,ub,N);
plot(xval,psi)
title('Mexican Hat Wavelet');

See Also

Introduced before R2006a

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