src/gmxlib/invsqrt_test.c

   1 /*
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  35 /* This file is completely threadsafe - keep it that way! */
  36 #ifdef HAVE_CONFIG_H
  37 #include <config.h>
  38 #endif
  39
  40 #include "vec.h"
  41
  42 int main(int argc,char *argv[])
  43 {
  44   real x,y,z,diff,av;
  45   int  i;
  46
  47   printf("%12s  %12s  %12s  %12s  %12s\n","X","invsqrt(X)","1/sqrt(X)","Abs. Diff.","Rel. Diff.");
  48   for(i=1; (i<1000); i++) {
  49     x = i*1.0;
  50     y = gmx_invsqrt(x);
  51     z = 1.0/sqrt(x);
  52     diff = y-z;
  53     av   = 0.5*(y+z);
  54     printf("%12.5e  %12.5e  %12.5e  %12.5e  %12.5e\n",x,y,z,diff,diff/z);
  55   }
  56   return 0;
  57 }