mex-file creation

I was trying to create a mex-file, however I can't do it beacuse Matlab shows the following error: Class function_handle is not support by coder Type. I wrote the following script and functions to calculate the solution of non-linear equation.

clear
clc

ep=10^(-6); % tollerance
itermax=50; % number max of iterations
a=0; % a,b initial interval
b=2; 

[x,iter] = Bisection(@f,a,b,ep,itermax)

%%%functions

function [x,iter] = Bisection(f,a,b,ep,itermax)
%
% Function for the solution of the non-linear equation  
%                       f(x)=0
% by the BISECTION method
%
% INPUT data: 
%    f     name of the MATLAB function implementing 
%          the non-linear function
%
%    a,b   initial interval [a,b]
%          such that f(a)f(b) < 0
%
%    ep    tolerance (>0)
%
% OUTPUT data:
%    x     solution of the non-linear equation
%    iter  number of performed iterations
%
fa = feval(f,a);
fb = feval(f,b);
if fa*fb > 0
    fprintf('\n\nThe initial interval does not satisfy f(a)f(b) < 0.')
    return
end

iter=0;
%   while abs(a-b) > ep+eps*max(abs(a),abs(b))
while abs(a-b) >= 2*ep && (iter < itermax)
    mid = (a+b)/2;
    fmid = feval(f,mid);
    if fa*fmid<=0
        % root in [a,mid].
        b  = mid;
        fb = fmid;
    else
        % root in [mid,b].
        a  = mid;
        fa = fmid;
    end
    iter=iter+1;
end
x = (a+b)/2;

function [ y ] = f( x )
y=x.^2-1;
end

[Jan]

You forgot to mention, when the error occurs. Do I understand correctly, that the shown code works reliable in Matlab and it fails only, if you try to compile it? Then please explain, if compiling is really needed.

Answer 1

[Jan]

The usage of function handles is limited, if you use the coder:

• https://www.mathworks.com/help/simulink/ug/function-handle-limitations-for-code-generation.html
• https://www.mathworks.com/help/coder/ug/matlab-language-features-supported-for-code-generation.html

Did you consider these limitations? If so, how can we help you? Perhaps this helps:

https://www.mathworks.com/matlabcentral/answers/256647-ode45-matlab-coder-function-handle

[dario cecchetti]

Exactly. I would like to convert the matlab code to mex-file because it is an exam request. Probably not yet need to make code conversion, however, the script will deem much larger and analyze many data. Anyway, the error reported by matlab occurs when I try to compile the new code. I do not know where to enter "% # codegen".

Thanks you very much for your time.

[Jan]

Did you read my answer?

[dario cecchetti]

of course, I answered at your following answer "You forgot to mention, when the error occurs. Do I understand correctly, that the shown code works reliable in Matlab and it fails only, if you try to compile it? Then please explain, if compiling is really needed." Then I checked your second answer and I couldn't to solve it. I'm sorry but my english it's not very good.