Question

I am writing a function with two arguments and I want the second argument to be processed as a string. The following code encounters an error

function Derivative = derive ( Matrix9x1 , string Variable )
end

How can I tell it to matlab?
I mean even if the user inputs 1 as the second argument it should be processed as an string
and the user should be able to enter for example omega

Answer 1

The second argument to your function will only be processed ‘as a string’ if it ‘is a string’, that is if you enclose it in single quotation marks. If you want to pass a number to a function and turn it into a string for further operations, use the function num2str. If you want to write a function which takes different actions depending on the type of the second argument you’re going to have to test that type when the function is called; you might want to look at the functions ischar, isstrprop, isnumeric, and their relations.

Oh, and don’t forget that a Matlab ‘string’ is really an array of characters which are just a convenience ‘type’ for integers-representing-characters.