Play audio slide show -- Keyboard shortcut: 'x'  Back to notes -- Keyboard shortcut: 'u'              Play sound for this slide -- Keyboard shortcut: 'y'  Lecture 9 - slide 4 : 31
Program 2
 

sqrt(x: Real) -> Real

  precondition: x >= 0;

  postcondition: abs(result * result - x) <= 0.000001