Pass a function as argument Matlab6.1

Hello! I'm studing matlab and I get some problem with a code.

First, I've created f1.m:

    function y = f1(x)
       
y = exp(x) - pi;
    
end

Then, I built a code to find the roots by bisector method:

function [root, err, n] = bissect(f, a, b, errMax)


    
m = (a+b)/2;
    
err = (b-a)/2;
    
n = 0;



while err > errMax


    
if f(a)*f(m) > 0
        
a = m;
    
else
        
b = m;
    
end

    
m = (a+b)/2;
    
err = (b-a)/2;
    
n = n + 1;

end


root = m;

end

But, when i run

>> [r,err,n] = bissect(@f1, 1, 2, 0.1);

it returns:

Warning: Subscript indices must be integer values.
>In C:\matlabR12\work\Codigo\bissect.m at line 12
??? Index exceeds matrix dimensions.
Error in ==> C:\matlabR12\work\Codigo\bissect.m
On line 12 ==> if f(a)*f(m) > 0

What am I doing wrong? I'm using Matlab R12

Answer 1

[Walter Roberson]

Looking at an old document https://web.stanford.edu/class/ee254/software/using_ml.pdf it appears that in R12, function handles existed, but that you needed to use feval() with them, such as

if feval(f,a)*feval(f,m) > 0