A problem including an array

I'm a C++ programmer, but never worked with MATLAB before, I have a problem to solve but I don't know the syntax very well. So, here is the problem: I have to input an array A(6,6) from the keyboard. If the result of multiplication of the elements in the main diagonal is greater than the sum of the smallest and the biggest element in the array, to calculate the function graphically: y = (A(3,1)/sqrt(3)A(2,2))*x^2+A(2,4)*x-8 for x is element of [-3:3] and delta x = 0.25. It is really easy to do that on C and C++ but I have a real hard time doing it on MATLAB. I would be really grateful if someone help me out. Thank you!

Answer 1

[Roger Stafford]

 if prod(diag(A)) > min(A(:)) + max(A(:))
  x = [-3:.25:3];  % or linspace(-3,3,25)
  y = A(3,1)/sqrt(3)*A(2,2)*x.^2 + A(2,4)*x - 8;
  plot(x,y)
 else
  % Whatever is to happen if the test fails
 end

(I assume A(2,2) is to be in the numerator in your notation.)

[Dimitar Dimitrov]

Thank you very much!