# What is the equation for Mexican hat wavelet defined by 'mexihat' function

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Palguna Gopireddy on 30 Mar 2022
Commented: Palguna Gopireddy on 13 Jun 2022
I am wondering what would be the equation for the Mexican hat wavelet defined by 'mexihat' function as its equation is not given in the discription. Not just this function, for some other functions also equations are not given.
I have done the following way, both are not equal and also I am unable to put [lb,ub] variables in the equation.
L=45;
alpha=2.5;
n=-(L-1)/2:(L-1)/2;
sigma=((L-1)/(2*alpha));
m=(1-(n/sigma).^2).*exp(-((n/sigma).^2)/2);
m=m.';
[m_r,x] = mexihat(-1,1,45);
m_r=m_r.';

Maria Lucia Cardinali on 9 Jun 2022
Edited: Maria Lucia Cardinali on 9 Jun 2022
If you open mexihat, you can see that the value is calculated as:
out2 = linspace(LB,UB,N); % wavelet support.
out1 = out2.^2;
out1 = (2/(sqrt(3)*pi^0.25)) * exp(-out1/2) .* (1-out1);
The formula is: , for .
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Palguna Gopireddy on 13 Jun 2022
Could you tell how to find the equation for chebwin function.
It is using 'chebwinx' after opening it.