You are a veritable font of knowledge, Peter.  (^&

However, I do have one quibble:

> >16. Write a program that takes inout two 3X3 matrices and display
> >    the sum.
>
> printf("23");

That should be:

printf ("{{a11 + b11, b12 + a12, 3a13 + b13 - 2a13},\n"
        " {a21 + aww, you know the rest...},\n"
        " {ditto}};\n");
printf ("If you invert me, I shall tickle you.\n");

Really...



  ``I probably don't know what I'm talking about.'' --rauch@math.rice.edu