mex-file creation

Question

dario cecchetti 2017-11-13

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/366696-mex-file-creation

关闭： MATLAB Answer Bot 2021-8-20

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

1 个评论
显示 -1更早的评论隐藏 -1更早的评论

Jan 2017-11-13

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.

此问题已关闭。

Answer 1

Jan 2017-11-13

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/366696-mex-file-creation#answer_290815

编辑：Jan 2017-11-13

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

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

3 个评论
显示 1更早的评论隐藏 1更早的评论

Jan 2017-11-13

Did you read my answer?

dario cecchetti 2017-11-13

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.