MATLAB: Bug in normpdf function

Question

Hi all,

I have encountered a weird issue using normpdf function for small sigma values, The code aims to create a dataset of "gaussian pulses" (different mu but same sigma)

sigma = 0.001 ;     % constant sigma
D = 100 ;           % Dimension of 1 pulse
I = linspace(0,1,D);% Interval
n = 30 ;            % number of pulse
pulse_dataset = zeros(n,D); %initializing the dataset
for i = 1:n 
    mu = rand(); %generate random mu in intervall [0,1]
    pulse_dataset(i,:) = normpdf(I, mu, sigma);
end
figure;
for i=1:n
    plot(I,pulse_dataset(i,:));
    hold on
end

This code outputs :

Since sigma is constant, why the pulses have not the same shape ?

Thanks for you help,

Answer 1

The height of the peaks depends on how small min(I-mu) is. Choosing D->Inf (e.g. D=10000), the shape of the pulses should become similar.

Best wishes

Torsten.