Your code works when I run it.
That you are getting the error: ‘Array indices must be positive integers or logical values.’ leads me to believe that you have a variable named ‘tan’ in your workspace. This is called ‘overshadowing’ a function.
To find out, run this from your Command Window or a script:
which tan -all
If the first result is:
tan is a variable.
You have found the problem. You then have to rename the ‘tan’ variable to something meaningful, and so the name does not ‘overshadow’ any MATLAB functions.
