Function having string as argument

Hi there,

I am making a function called 'derr' which calculates derivative of the function given in the argument as string.

function = derr('name of function');

example if 'sin' is given as argument this function should calculate derivative of sin.

calling of function should be like : derr('sin')

How can I do that?

Thank you.

Answer 1

[Stephen23]

I would not recommend using a string to define the input function.

A much more reliable way would be to write your code to accept a function handle (which is the correct variable type for holding functions):

https://www.mathworks.com/help/matlab/function-handles.html

For example, define your function something like this:

function out = myfun(fun)
assert(isa(fun,'function_handle'),'Input must be a function handle')
out = fun(pi); % do whatever you want with the function handle...
end

and then simply call your function using any function handle:

myfun(@sin)
myfun(@cos)
myfun(@sqrt)
myfun(@(n)3*(n.^2))

If you really want to limit the user to using strings (not designed for holding functions) then consider using str2func or switch inside your function.