Hi,
how about this:

#!/usr/bin/perl -w
 
use strict;

my @line;
my $k = 0;
while (<DATA>) {
    chomp;
    $line[++$k] = [ split(/\s+/) ];
}

my $output = '';

for (my $i = 1; $i <= 35; ++$i) {
    for (my $j = 1; $j <= 35; ++$j) {
        if ( $line[$i][$j] ) {
            $output .= $line[$i][$j] . "\t";
        }
        else {
            $output .= "0\t";
        }
    }
    $output .= "\n";
}

print $output;


__DATA__
 2.8017         0         0         0         0         0         0
         0    1.2969         0         0         0         0         0
         0         0    0.5495         0         0         0         0
         0         0         0    0.2329         0         0         0
         0         0         0         0    0.1953         0         0
         0         0         0         0         0    0.1723         0
         0         0         0         0         0         0    0.0959
[download]

Cheers,
Sven