Errors in Menu program

Hi all,

I'm a newbie to Matlab and wrote a program using menu as follows:

*eapplication.m*

choice = eoption;

while choice ~= 4

    switch choice

        case 1
            explaine;

        case 2
            limite;

        case 3
            x = input('Please enter a value for x: ');
            expfn(x);
    end

    choice = eoption;

end

*eoption.m*

choice = menu('Choose an e option', 'Explanation', 'Limit', ... 'Exponential function', 'Exit Program');

while choice == 0

disp('Error - please choose one option.')

choice = menu('Choose an e option', 'Explanation', 'Limit', ... 'Exponential function', 'Exit Program'); end

*It gave me an error: ??? Attempt to execute SCRIPT eoption as a function: C:\Documents and Settings\Olive\My Documents\MATLAB\eoption.m

Error in ==> eapplication at 1 choice = eoption;*

Could you please shed some lights?

Thanks heaps.

Oliver.

Answer 1

[Matt Tearle]

Pretty much what it says. The line choice = eoption; implies that eoption is a function call (because it is asking for an output, to be assigned to choice). But eoption is a script, not a function.

The difference is in how variables are managed. Scripts work with the base MATLAB workspace. Functions use local workspaces, so variables are local. So your options are:

1. Turn eoption into a function by adding the line function choice = eoption at the beginning.
2. Leave eoption as a script and inherit choice from the base workspace. Hence, change the line choice = eoption; (in eapplication) to just eoption;

[Oliver]

Thank you so much Matt. You're wonderful. Can you recommend good books for me? I've got Matlab: a practical introduction to programming and problem solving and Matlab programming for Engineers. Both have errors.

[Matt Tearle]

There are a lot of books out there, as well as other resources. Are you in academia or industry? And you're in engineering (or did you just happen to have an engineering MATLAB book)?

http://www.mathworks.com/support/books/index_by_categorytitle.html?category=17&sortby=title

Answer 2

[Jose Jeremias Caballero]

Hello

clear all
clc
choice = menu('Choose a opcion','explaine','limite','expfun','exit of menu');
    switch choice
        case 1
            explaine='matlab';
            display(explaine);

          case 2
              syms x
              limit((x-2)/(x^2-4),2)
          case 3
              x = input('Please enter a value for x: ');
              expfn=inline('sin(x)+5');
              expfn(x)
          otherwise 
              display('thanks');
      end