src/gmxlib/invsqrt_test.c

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  38 /* This file is completely threadsafe - keep it that way! */
  39 #ifdef HAVE_CONFIG_H
  40 #include <config.h>
  41 #endif
  42
  43 #include "vec.h"
  44
  45 int main(int argc,char *argv[])
  46 {
  47   real x,y,z,diff,av;
  48   int  i;
  49
  50   printf("%12s  %12s  %12s  %12s  %12s\n","X","invsqrt(X)","1/sqrt(X)","Abs. Diff.","Rel. Diff.");
  51   for(i=1; (i<1000); i++) {
  52     x = i*1.0;
  53     y = gmx_invsqrt(x);
  54     z = 1.0/sqrt(x);
  55     diff = y-z;
  56     av   = 0.5*(y+z);
  57     printf("%12.5e  %12.5e  %12.5e  %12.5e  %12.5e\n",x,y,z,diff,diff/z);
  58   }
  59   return 0;
  60 }