c  From: "COMPUTATIONAL PHYSICS, 2nd Ed" 
c  by RH Landau, MJ Paez, and CC Bordeianu 
c  Copyright Wiley-VCH, 2007.
c  Electronic Materials copyright: R Landau, Oregon State Univ, 2007;
c  MJ Paez, Univ Antioquia, 2007; and CC Bordeianu, Univ Bucharest, 2007.
c  Support by National Science Foundation                          
c                                                                   
c  area.f: Area of a circle, r input from terminal                 
c
      Program area
			
        Double Precision pi, r, A
c                            Best value of pi for IEEE floating point
        pi = 3.1415926535897932385E0
c                               read r from standard input (terminal)
         Write(*,*) 'Enter the radius of a circle'
         Read (*,*)  r
c                                                      calculate area
         A = pi * r**2
c                                    write area onto terminal screen
         Write(*, 10) 'radius r = ', r, 'area = ', A
 10      Format(a10, f10.5, a10, f12.5)
         Stop 'area'
       End