Function index is a string, why?

function [ Xs ] = RegulaRaiz( Fun,a,b,ErrMax )

imax=100;

Fa= Fun(a)

Fb=Fun(b)

The code for fun is:

function y = Fun(x)

y = (sin(x)/(3*x))-0.25;

end

If I call the function as RegulaRaiz( 'Fun',1,2,0.0001 )

Fa becomes f and fb becomes u, how do i fix this?

Answer 1

[michio]

The first input 'Fun' to the function RegulaRaiz is 1x3 char, 'Fun'. So Fa = Fun(1) is f and, Fb = Fun(2) = u.

Could you try

RegulaRaiz(@(x) Fun(x),1,2,0.0001)

instead? Specify the function as an input using a function handle @(x) Fun(x).

[Vitor Braz]

Thank you!

[Jan]

Or simpler and faster:

RegulaRaiz(@Fun,1,2,0.0001)

Answer 2

[Adam]

Why are you naming a variable passed to your function the same as a function? The string you pass in as the variable 'Fun' is hiding the function so

Fa= Fun(a);

is trying to index into 'Fun' so Fun(a) is Fun(1) which is 'F' and Fun(b) is Fun(2) which is 'u'.