Code for an indicator transform using an existing Gaussian Distribution

I have this code for a Gaussian distribution and I wish to transform it into an Indicator transform so that I can use ranges assigned for the indicators to do my work. Please how can I code the indicator transform from an existing Gaussian distribution using Matlab?

mu1 = 45;

sigma1 = 31;

samplesize1 = 100;

randvals1 = randn(samplesize1,1)*sigma1 + mu1;

histogram(randvals1);