Problem on code while plotting a graph

I am plotting a graph, with the line:

 figure;
 hold on ;
 .....
 title('function');
 .....
 hold off;

But I ended up with an error of "Index exceeds array bounds." on the title line. How can I solve this?

[Angus Wong]

This is my code:

    figure;

    hold on;

    fplot(y,[xmin xmax]);

    ylim([ymin ymax]);

    title('function');

    xlabel('x');

    ylabel('f(x)');

    hold off;

The error message is:

 Index exceeds array bounds.

 Error in lagrangianinterpolation2 (line 113)
     title('function');

[Paolo]

 figure;
 hold on ;
 title('function');
 hold off;

Works fine on my machine with 2017b, what Matlab version are you using?

[Angus Wong]

2018a

[Paolo]

Star Strider is right, the error is probably not related to the title command.

Answer 1

[Star Strider]

The actual error is most likely in the line just above your title call.

Check it to be certain it is entered correctly.

EDIT — (16:10 UCT)

What is your ‘y’ function?

Note that in your code, and using fplot, ‘y’ must be a function of one variable.

[Angus Wong]

I defined y as:

 y=@(x)(p1*x+p0);

Written on the line just before the line 'figure;'

[Angus Wong]

The codes are:

    t1=A(2,1)/(A(1,1)-A(1,2));

    t2=A(2,2)/(A(1,2)-A(1,1));

    p1=t1+t2;

    p0=-t1*A(1,2)-t2*A(1,1);

    if p1==inf || p1==-inf || isnan(p1)==1

        uiwait(msgbox('Error. Rerun the program.','Error!','error'));

        p1=0;

        p0=0;

        yf1=0;

        yf2=0;

        yf3=0;

        return;

    end

    if abs(p1)<10^-10

        p1=0;

    end

    if abs(p0)<10^-10

       p0=0;

    end

    fprintf(1,'The equation is f(x) = %g x + %g . \n',p1,p0);

    disp(' ');

    xmin=min(A(1,:))-1;

    xmax=max(A(1,:))+1;

    ymin=min(A(2,:))-2;

    ymax=max(A(2,:))+2;

    y=@(x)(p1*x+p0);

    figure;

    .....

Where A is a 2 by 2 matrix full of numbers.

[Angus Wong]

Thanks guys, I know where I made the mistake.

[Star Strider]

As always, my (our) pleasure.