below is my script. the incrementation loop works correctly until it hits 5.9 then it increments incorrectly just there. sample output follows the code. 

#!/usr/bin/perl
# zeta.pl  c.2011 stan kulikowski ii, stankuli@etherways.com, pensacol
+a, fl 32514


$SERIES_DEPTH = 1000000;
&QUERY_DIRICHLET;


sub QUERY_DIRICHLET
{
  my $POWERS = 1;
  my $PRECISION = 0;

  print "\n Dirichlet's zeta function. \n";

  my $OK = 0;

  until ($OK)
  {
    print " How many powers : ";
    chop($POWERS = <>);
    $POWERS = int $POWERS;

    ($POWERS > 1) ? $OK = 1 : print " value must be greater than 1 \n"
+;
  } # until $OK #

  $OK = 0;
  until ($OK)
  {
    print " To what precision : ";
    chop($PRECISION = <>);

    ($PRECISION < 1 && $PRECISION > 0) ? $OK = 1 : print " value must 
+be between 1 and 0 \n";
  } # until $OK #

  &DIRICHLET ($POWERS,$PRECISION);
  print "\n\n"; 

} # QUERY_DIRICHLET #


sub HARMONIC_SERIES
{
  my ($POWER) = @_;

  my $RESULT = 1;
  my $SERIES = $SERIES_DEPTH;

  while ($SERIES > 1)
  {
    $RESULT += 1/($SERIES-- **$POWER);
  } # while ($SERIES > 1) #
  return $RESULT;
} # HARMONIC_SERIES #


sub DIRICHLET
{
  my ($POWERS,$PRECISION) = @_;
  my $POWER = 2;

  print "\n\n\t Power \t Dirichlet's zeta result  (harmonic series dep
+th = $SERIES_DEPTH)\n\n";

  while ($POWER < $POWERS+1)
  {
    print "\t $POWER \t " . &HARMONIC_SERIES ($POWER) . " \n";
    $POWER += $PRECISION;          # problem here at 5.9?
  } # while ($POWER <= $POWERS) #  
} # DIRICHLET #


# eof zeta.pl

[download]

here is what the output looks like: 



 Dirichlet's zeta function. 
 How many powers : 6
 To what precision : 0.1


     Power      Dirichlet's zeta result  (harmonic series depth = 1000
+000)

     2      1.64493306684877 
     2.1      1.56021630515022 
     2.2      1.49054320392715 
     2.3      1.43241778712389 
     2.4      1.38334285599691 
     2.5      1.34148725658587 
     2.6      1.30547780891302 
     2.7      1.27426464440048 
     2.8      1.24703142229228 
     2.9      1.22313389528938 
     3      1.20205690315031 
     3.1      1.18338365210598 
     3.2      1.16677337098058 
     3.3      1.15194479471816 
     3.4      1.13866377572624 
     3.5      1.12673386731579 
     3.6      1.11598907912243 
     3.7      1.10628824146401 
     3.8      1.09751057645852 
     3.9      1.08955218466995 
     4      1.08232323371086 
     4.1      1.07574569034329 
     4.2      1.06975147723364 
     4.3      1.0642809643257 
     4.4      1.05928172597973 
     4.5      1.05470751076137 
     4.6      1.0505173825665 
     4.7      1.04667500069907 
     4.8      1.04314801333513 
     4.9      1.03990754404931 
     5      1.03692775514334 
     5.1      1.03418547468746 
     5.2      1.03165987667789 
     5.3      1.0293322056832 
     5.4      1.02718553892034 
     5.5      1.02520457995467 
     5.6      1.02337547922702 
     5.7      1.02168567742621 
     5.8      1.02012376838834 
     5.9      1.01867937874473 
     5.99999999999999      1.01734306198444 
     6.09999999999999      1.0161062049622 
     6.19999999999999      1.01496094518522 
     6.29999999999999      1.0139000974628 
     6.39999999999999      1.01291708871218 
     6.49999999999999      1.01200589988852 
     6.59999999999999      1.01116101415427 
     6.69999999999999      1.01037737052638 
     6.79999999999999      1.00965032234471 
     6.89999999999999      1.00897559999333 
     6.99999999999999      1.00834927738192

[download]

In reply to incrementation loop fails? by stankuli

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