#!/usr/bin/perl

if(0){
  $a=1.0;
  $b=0.1;
  foreach $i (1..50){
    $b=$b/2.0;
    $c=$a+$b;
    print "$i $b $c\n";
  }
  exit;
}

if(0){    #...... use if
  $a=1.0;
  $b=0.1;
  for($i=0;$i<55;$i++){
    $b=$b/2.0;
    $c=$a+$b;
    print "$i  $b $c\n";
    if( $a == $c){ print "now \$a and \$c are equal!\n"; last; }  #... break out the loop
  }  exit;
}

if(0){   #...... use formats
  $a=1.0;
  $b=0.1;
  for($i=0;$i<55;$i++){
    $b=$b/2.0;
    $c=$a+$b;
    printf "%5d %30.25f %30.25f %30.25f\n",$i,$a,$b,$c;
    if( $a == $c){ last; }  #... break out the loop
  }   exit;
}

if(0){  #....... use an array, and write compact
  $a=1.0; $b=0.1; for($i=0;$i<55;$i++){ $b=$b/2.0; $c=$a+$b;  $arr[$i]=$c; }
  $k=0; foreach $x (@arr){ printf "%d %30.25f\n",$k,$x; $k++; if( $x == $a){ last; } }
  exit;
}

if(1){  #....... use function
  $a=1.0; $b=0.1; for($i=0;$i<55;$i++){ $b=$b/2.0; $c=$a+$b;  $arr[$i]=$c; }
  $z1=111; $z2=222;
  @ret=func_compare($a,@arr);
  $meq=shift(@ret); $mne=shift(@ret);  #... get the 2 scalars back
  print "after func_compare:  z1=$z1  z2=$z2 (which one changed?) meq=$meq  mne=$mne \n";
  #...... print the fomp array
  foreach(@ret){ print " $_ "; }  print "\n";
  exit;
}

#...... functions, how to hand back results, local vars
sub func_compare{  local($z)=shift(@_);  local(@y)=@_;
    local($x,$i,@r,$k);
    local($z1);   $z1=555;  $z2=666;
    print "\$b = $b is a global variable!\n";
    local($neq,$nne); $neq=0; $nne=0; $k=0;
    foreach $x (@arr){ if($x == $a){ $neq++; $r[$k]="${k}-->eq";  printf(" they are equal    %30.25f %30.25f\n", $a,$x); }
                       if($x != $a){ $nne++; $r[$k]="${k}-->ne";  printf(" they are not eq.  %30.25f %30.25f\n", $a,$x); } $k++; }
    return( ($neq,$nne,@r) );
}