Try

#!perl
use strict;

my @array = qw(
-- 0.0175 0.0483 0.0507
-- 0.0471 0.0483
-- 0.0287
--);

my @column;
my $curr_column = 0;
my $rows = 0;
while (@array) {
  if( $array[0] ne '--' ) {
    push @{ $column[ $curr_column ] }, shift @array;
    if( $rows < $#{ $column[ $curr_column ] } ) {
      $rows = $#{ $column[ $curr_column ] };
    };
  } else {
    $curr_column++;
    $column[ $curr_column] ||= [0]; # a new column
    shift @array;
  };
};

for my $row (0..$rows) {
  my @tmp = ();
  for (@column){
    if ( exists ($_->[ $row - $rows -1 ]) ){
      push @tmp,$_->[ $row - $rows - 1 ];
    }
  }
  print join "\t", @tmp;
  print "\n";
};
[download]

PERFECT! Among my array I insert at the start of the code:

chomp @array
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because I have the newline. Thank you to everybody! ...if you want can you explain me the code?...

The previous post by poj prints:

0
0.0175    0
0.0483    0.0471    0
0.0507    0.0483    0.0287    0
[download]

I don't see anywhere in your spec where these extra zeroes are required or even desired!
Please be very specific about the requirements.

I recommend something like this:

#!/usr/bin/perl
use strict;
use warnings;

my @array = qw(
-- 0.0175 0.0483 0.0507
-- 0.0471 0.0483
-- 0.0287
--);

my @twod_array;

my $i_col = -1;
my $i_row;

foreach my $ele (@array)
{
   if ($ele eq '--')
   {
      $i_col++;         #new column starts
      $i_row = $i_col;
      next;
   }
   
   $twod_array[$i_row++][$i_col] = $ele;
}

foreach my $row_ref (@twod_array)
{
   print join ("\t",@$row_ref),"\n";
}


__END__
0.0175
0.0483    0.0471
0.0507    0.0483    0.0287
[download]