Question

I’m new to MATLAB and I am having the following difficulty: I would like to have a graph of a function plotted but I keep getting the error that “Matrix dimensions must agree.”

The code I am using is as follows:

x = -1.5:0.1:1.5;
y = 1/sqrt(9 - x.^2) + 1/sqrt(4 - x.^2) - 1;
plot(x, y);

The error as it appears in the command window is:

Error using  / 
Matrix dimensions must agree.

Possibly the problem lies where I define x = -1.5:0.1:1.5; which makes MATLAB thinks this is a matrix, but all I want to do is have function values plotted at intervals of 0.1 between -1.5 and 1.5.

How can I get around this problem?

Answer 1

Operations like multiplication or division can have special meaning for matrices. If you’re interested in “normal”, element-wise operations, you need to use the dot before the operator, i.e.

 y = 1./sqrt(9 - x.^2) + 1./sqrt(4 - x.^2) - 1;