Simple symbolic object question

Hi!

I have got a function:

function Iak= Ia(k)

syms A0;
if (even(k))
    Iak=0;
else
    Iak=(2*A0)/(k^2*pi^2);
end

end

even(k) is implemented well, returns 1 if k is even, 0 if it's not. I expected for (2*A0)/9.9896 as answer of Ik(1). But Matlab gives:

(562949953421312*A)/2778046668940015

Why? What is wrong with my function?

Answer 1

[Walter Roberson]

The Symbolic Engine automatically combines all numeric multipliers and dividers, so 2/9.9896 is calculated and shown in numeric form.

The Symbolic Engine automatically converts floating point values into rational values unless you take care otherwise, and "pi" is a floating point value.

I suggest,

function Iak= Ia(k)

    syms A0;
    if (even(k))
        Iak = sym(0);
    else
        Iak = (2*A0)/(k^2*sym('pi')^2);
    end

end

[Peter]

Thank you :-)