src/gmxlib/tstsqrtc.c

   1 /*
   2  * $Id$
   3  *
   4  *       This source code is part of
   5  *
   6  *        G   R   O   M   A   C   S
   7  *
   8  * GROningen MAchine for Chemical Simulations
   9  *
  10  *               VERSION 2.0
  11  *
  12  * Copyright (c) 1991-1999
  13  * BIOSON Research Institute, Dept. of Biophysical Chemistry
  14  * University of Groningen, The Netherlands
  15  *
  16  * Please refer to:
  17  * GROMACS: A message-passing parallel molecular dynamics implementation
  18  * H.J.C. Berendsen, D. van der Spoel and R. van Drunen
  19  * Comp. Phys. Comm. 91, 43-56 (1995)
  20  *
  21  * Also check out our WWW page:
  22  * http://md.chem.rug.nl/~gmx
  23  * or e-mail to:
  24  * gromacs@chem.rug.nl
  25  *
  26  * And Hey:
  27  * Green Red Orange Magenta Azure Cyan Skyblue
  28  */
  29 static char *SRCID_tstsqrtc_c = "$Id$";
  30
  31 #include "vec.h"
  32 #include "lutab.h"
  33
  34 int main(int argc,char *argv[])
  35 {
  36   real x,y,z,diff,av;
  37   int  i;
  38
  39   init_lookup_table(stdout);
  40   printf("%12s  %12s  %12s  %12s  %12s\n","X","Y","Z","Dy","Dy/Z");
  41   for(i=1; (i<1000); i++) {
  42     x = i*1.0;
  43     y = invsqrt(x);
  44     z = 1.0/sqrt(x);
  45     diff = y-z;
  46     av   = 0.5*(y+z);
  47     printf("%12.5e  %12.5e  %12.5e  %12.5e  %12.5e\n",x,y,z,diff,diff/z);
  48   }
  49 }