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 diff.f: Differentiation; forward, central & extrapolated differnc c results saved as x y1 y2 y3 Program diff Implicit None c h stepsize for approximation, xrange and xstepsize Real*8 f, h, result(3), x, xmin, xmax, xstep Open(6, File = 'diff.dat', Status = 'Unknown') h = 1.e-5 xmin = 0.0 xmax = 7.0 xstep = 0.01 Do 10 x = xmin, xmax, xstep result(1) = (f(x+h) - f(x))/h result(2) = (f(x+h/2) - f(x-h/2))/h result(3) = (8*(f(x+h/4)-f(x-h/4))-(f(x+h/2)-f(x-h/2)))/(3*h) Write (6, 20) x, result(1), result(2), result(3) 10 Continue 20 Format(F5.3, TR4, F10.8, TR4, F10.8, TR4, F10.8) Close(6) Stop 'data saved in diff.dat' End c c the function to integrate Function f(x) Implicit none Real*8 f, x f = cos(x) Return End