Functions

Fotran has some intrinsic (or built-in) functions

• $+, * , **, ...$
• Mod(x,y), Sin(x), ...

Why do we need so many? Can we not do the following?

  ! for I = 2 * 3               !for I = m * n
  I = 2 + 2 + 2                 I = 0
                                Do J = 1, n
                                  I = I + m
                                End Do

Inconvenient?

What are user defined functions? Why do we need