Nested function error in matlab

Question

I'm trying to make a function in MATLAB for solving 2 equations using successive substitution. However, I am getting a nested function error( function NLSS), even though the function isn't nested. Here is the code:

X=[0.75 0.25]; %N-dimensional array, first guess then solution

Y=[0 0];

G(1)=(sqrt(1-(X(2))^2)); %right hand side functions
G(2)=1-X(1); %right hand side functions

MAXIT=10;

ITEST=1;

function [X,counter] =NLSS(X,Y);
    while ITEST==1
        counter=0;
        counter=counter+1;
        X(1)=(sqrt(1-(X(2))^2));
        X(2)=1-X(1);

            if abs(Y(1)-X(1))<0.00000001
                ITEST=3;
            end

            if counter>MAXIT
                ITEST=2;
            end

        Y(1)=X(1);
        Y(2)=X(2);        

    end;
end;

fprintf('answer for X1 is %d  and X2 is %d and ITEST is %d.\n',X(1),X(2),ITEST);
fprintf('number of interations is %d.\n',counter);

Dan · Accepted Answer · 2016-01-18 15:07:00Z

3

The function is nested because you have code before you use the function keyword. In MATLAB, you can not have a function inside a script. You can nest a function in another function and you can have a local function, which is declared after another function. A function must be in a file (strongly recommended that file name matches the function name) and the first line of that file is the function ... = ...(...) line. See the docs for more.

To fix your error, create a file called NLSS.m with the following code

function [X,ITEST,counter] =NLSS(X,Y,ITEST,MAXIT);
    while ITEST==1
        counter=0;
        counter=counter+1;
        X(1)=(sqrt(1-(X(2))^2));
        X(2)=1-X(1);

            if abs(Y(1)-X(1))<0.00000001
                ITEST=3;
            end

            if counter>MAXIT
                ITEST=2;
            end

        Y(1)=X(1);
        Y(2)=X(2);        

    end
end

And then change your original script to

X=[0.75 0.25]; %N-dimensional array, first guess then solution

Y=[0 0];

G(1)=(sqrt(1-(X(2))^2)); %right hand side functions
G(2)=1-X(1); %right hand side functions

MAXIT=10;

[X,ITEST,counter] =NLSS(X,Y,ISTEST,MAXIT);

fprintf('answer for X1 is %d  and X2 is %d and ITEST is %d.\n',X(1),X(2),ITEST);
fprintf('number of interations is %d.\n',counter);

Note that you function has to be in your current working directory, i.e. the directory that your script is running from.

edited Jan 18, 2016 at 15:07

answered Jan 18, 2016 at 6:24

Dan

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1 Comment

user2606257 Over a year ago

Thanks, your code worked. I just had to add ITEST in the output for the function code.

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