How to plot PDF and CDF for a normal distribution in matlab

cdf, matlab, normal-distribution

Solution

Your function `plotNormPDF` is correct except that you should not divide by the maximum. As David Marx wrote, there is no upper constraint on the values that a probability density function can attain, only a constraint regarding its integral over the range of possible values.

function plotNormPDF(u,s,color)
mu = u;
sigma = s;
x = (mu - 5 * sigma) : (sigma / 100) : (mu + 5 * sigma);
pdfNormal = normpdf(x, mu, sigma);
string = 'the maximal pdfNormal is';
string = sprintf('%s :%d', string,max(pdfNormal));
disp(string)
plot(x, pdfNormal,color);
end

Your function `plotNormCDF` is correct in principle, but probably not very precise because it approximates an integral by a cumulative sum. Better to use the function `normcdf`. Normalization of the maximum to 1 here is neither necessary nor does it have an effect.

function plotNormCDF(u,s,color)
mu = u;
sigma = s;
x = (mu -  5*sigma) : (sigma / 100) : (mu + 5*sigma);
cdfNormal = normcdf(x, mu, sigma);
plot(x,cdfNormal,color)
end

Problem

Original source