Index exceeds matrix dimensions. Please help.

Here is my code:

disp('Choose one of the following options:');
a1=0;
while(a1~=4)
    disp('press 1 for enter sides and shape code:');
    disp('press 2 for diplay area:');
    disp('press 3 for diplay perimeter:');
    disp('press 4 for exit:');
    *a1=input('Please Enter Your Selection:');*
    if (a1==1)
        v1=input('Enter value of side1:');
        v2=input('Enter value of side2:');
        v3=input('Enter the shape code(t/T for triangle r/R for rectangle:','s');
        r1=calcarea(v1,v2,v3);
        r2=calcperim(v1,v2,v3);
    end
    if (a1==2)
        disp(['The area is :',num2str(r1)]);
    end
    if (a1==3)
        disp(['The perimeter is :',num2str(r2)]);
    end
    if (a1==4)
        disp('Thank you for using Geometric calculator, Goodbye!');
    end
end

The error says: Index exceeds matrix dimensions Error in a1= input('Please enter your selection:'); I have highlighted for convenience.

Answer 1

[James Tursa]

Do you inadvertantly have a variable called "input" in your workspace?

[Derrick Edmiston]

yes so you can input the number you want to go to

[James Tursa]

You need to clear that "input" variable from the workspace so that MATLAB can call the "input" function. As it is now, when that line get executed MATLAB thinks you are trying to index into the variable called "input" ... MATLAB is not calling the "input" function which is what you want.

[Derrick Edmiston]

woops read that wrong sorry, and no

[James Tursa]

Are you sure? Type the following:

dbstop if error

Then run your code. When it pauses at the error, type "whos" at the command line to see what variables you have.