I know this isn't part of your question, but I also want to add that you should read perldoc perlvar, specifically the part on special variables $a and $b. Long story short, don't use variables with those names, they're reserved. Besides, they're horrible names. $x and $y are less horrible only because they have standard mathematical meanings.

Thus, your code should be more like this:

use strict;
use warnings; # important, too.

#-- variables and handles 
my @Matrix = map { [ (0) x 361 ] } 0..360;

#--Open the input and output files

# use 3-arg open, use lexical filehandle, don't interpolate a variable
# that doesn't need anything added to it, i.e., "$inf" is bad, but "$i
+nf-foo"
# is not, report WHY open fails, not merely that it has failed.
open my $in, '<', $foo or die "Can't read $inf: $!";

# lexical $line with minimal scope, check for definedness
# (if you have a line that is "0\n", you'll find your original code
# will terminate early).
while (defined (my $line = <IN>))
{
# usually, split ' ', $line is what you want instead of /\s+/.
# but they do slightly different things, so I'm not changing it.
# Added "my" so we create a new @result each time.
 my @result   = split(/\s+/, $line);

# I'm guessing here since I don't know where $phi and $psi really
# come from.
 my $phi = int($result[0]);
 my $psi = int($result[1]);

# use $ instead of @ to signify we want a scalar value from
# the array.  Use ++ instead of += 1 because it's more idiomatic
# though technically it's no big deal either way.
 $Matrix[$phi+180][$psi+180] ++;
   
}
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you mean i should do some thing like this ? :s

use strict;

#-- Define in/out files
my $inf = "test.txt" ;

#-- variables and handles 
my $line; my $a; my $b; my @result;

@row = ((0) x 361);
@column = ((0) x 361);
my @Matrix = ( @row, @column);

#--Open the input and output files
open (IN,  "$inf") || die "Can't read $inf";

while ($line = <IN>)
{
 @result   = split(/\s+/, $line);
 $a = $result[0]; 
 $a = int($phi);
 $b = $result[1];
 $b = int($psi);

@Matrix[$row[($a+180)]][$column[($b+180)]] += 1;
   
}
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Actually, your code has a number of problems.
• that isn't how you initialize a 2-dimensional array. your initialization of @matrix will make a 722 element 1d array. You would need something like: @matrix=map {[(0) x 361]} (0..361);
• From what I can see you want:  $Matrix[$a+180][$b+180] += 1;

I would suggest giving Modern Perl or Learning Perl and Programming Perl a good read to get down some of the fundamentals.

Update: Also you set $a and $b to values, then immediately set them to int($phi) and int($psi) which are undefined. If you were running with strict and warnings the compiler would have shown you that.



-pete
"Worry is like a rocking chair. It gives you something to do, but it doesn't get you anywhere."

@Matrix[$row($a+180)][$column($b+180)] += 1;

should be something like

$Matrix[$row($a+180)][$column($b+180)] += 1;

my @Matrix;
$Matrix[$a] = 1;
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