#!/usr/bin/perl
### TO PRODUCE THE INVERSE OF A SQUARE MATRIX (ANY SIZE) in PERL:
use warnings;
use math_module;
##################################
#  Inverse matrix calculation: 
##################################
print"\n Enter the Number of Rows i.e. 4 here: ";
$n= <STDIN>; chomp$n;
$N=$n;              
## Input the matrix text file: 
print "\n\n Please type the filename(.txt) i.e. d1.txt: ";
 $DNAfilename = <STDIN>;
 chomp $DNAfilename;         
## To remove white space:
$DNAfilename=~ s/\s//gis;
# open the file, or exit
 unless ( open(DNAFILE, $DNAfilename) ) {
 print "Cannot open file \"$DNAfilename\"\n\n";
 exit;
 } # Line 10
 @a = <DNAFILE>;
@m2=@a;
print"\n The contents of input matrix file are (array m2):\n\n 
@m2\n";
### Data Ends Here ###########################
@inv=math_module::get_inverse($N,@m2);
##############################################
# Checking if the inverse matrix is correct:   
##############################################
for ($i=0; $i<$N; $i++)
{                         
  for ($j=0; $j<$N; $j++)
  {
     $t=0;
     for($k=0; $k<$N; $k++)
     {
        $t=$t+ $m2[$i][$k]*$inv[$k][$j];  
     }   
  } 
}
################################################# 
# Output inverse matrix:  
##################################################
print "\n\n The Inverse Matrix is:\n\n";
## Use of for LOOP:   
for ($i=0; $i<$N; $i++)
{                   
  for ($j=0; $j<$N; $j++)
  {
      print $inv[$i][$j];
      print "  ";
  }
  print "\n\n";
}
exit;