Mexican hat (Ricker) wavelet
[PSI,X] = mexihat(LB,UB,N)
[PSI,X] = mexihat(LB,UB,N) returns values
of the Mexican hat wavelet on an
N point regular
X, in the interval
The Mexican hat wavelet is also known as the Ricker wavelet.
Output arguments are the wavelet function
on the grid
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.
You can use
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.
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');