// function
int square( int n ) {
   return n * n;
}

// procedure
void display( int n ) {
   printf( "The value is %d", n );
}

f(x)=(1+x)
g(x)=.5*(2+x/2)

-function
int sample(int value)
     {
      return value;
     }

--procedure
void display(int value)
     {
       echo("The value is ", value );
      }

// The following is pseudo code:
g(x) = {
  if (morning()) {
     g = 2 * x;
  }
  else {
   g = x;
  }
  return g;
}

// We can immediately translate this definition into a recursive procedure
// for computing Fibonacci numbers:

(define (fib n)
  (cond ((= n 0) 0)
        ((= n 1) 1)
        (else (+ (fib (- n 1))
                 (fib (- n 2))))))

make-pies (fruit, milk, flower, eggs, sugar, heat) = {
   return (heat (add fruit (mix eggs flower milk)))
}

A       function     is to a     machine
as a    procedure    is to a     recipe
as      attributes   are to      ingredients
as      output       is to       product