How can I define Y to be different for different X values like a histogram

Question

I'm trying to plot a probability mass function for the probability of certain sums when rolling three dices and I found this example in MathCad and wondered if there is anything like it in MatLab?

Answer 1

I imagine you’d build that as a lookup table rather than a series of if/else statements. It is easy to compute the probabilities using convolution:

f1 = ones(1,6);
f2 = conv(f1,f1);
f = conv(f2,f1);
% because f contains values from x=3 to 18,
% rather than starting at 1 as MATLAB arrays do,
% we add two zeros to the front:
f = [0,0,f];

Now f(x) returns the probability of throwing x.