#!/usr/bin/perl
use warnings;
use math_module;
### TO PRODUCE THE INVERSE OF A SQUARE MATRIX in PERL:
# In a square matrix the number of rows and columns are equal.
# Here we intend to get the inverse of a 4x4 square matrix.
######################################################
print"\n Here we intend to get the inverse of a 4x4 square matrix.\n";
print"\n Enter the Number of Rows i.e 4: ";
$n= <STDIN>; chomp$n;
$N=$n;              
# Input the matrix below:
$m2[0]=[3,2,1,1]; 
$m2[1]=[1,0,2,2];
$m2[2]=[4,1,3,3];
$m2[3]=[1,2,3,4];
### Data Ends Here ###########################
@inv=math_module::get_inverse($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];  
     }   
  } 
}
################################################# 
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;
##</code><code>##

package math_module;
sub get_det($\@)
{
my ($m__size, $m_matrix)=@_;
my $m_det=0;
my @new_matrix;
my $i_mat;
if ($m__size ==1)
{
   return $$m_matrix[0][0];  # Line 10 
}
if ( $m__size ==2)
{
       $m_det=$$m_matrix[0][0]*$$m_matrix[1][1]-$$m_matrix[0][1]*$$m_matrix[1][0];
       return $m_det;
}
else
{
       for ($i_mat=0; $i_mat<$m__size; $i_mat++)
       {                       # Line 20  
           for ($m_r=1; $m_r<$m__size; $m_r++)
           {
             my $k_ajust=0;    # Line 23 
             for ($m_k=0; $m_k < $m__size; $m_k++)
             {
                   if ($m_k != $i_mat)
                   {
                       $new_matrix[$m_r-1][$m_k-$k_ajust] =$$m_matrix[$m_r][$m_k];
                    }
                    else   # Line 30 
                    {   
                       $k_ajust=1;
                    }
             }
           }
       $m_det=$m_det + (-1)**(2+$i_mat) * $$m_matrix[0][$i_mat] * get_det($m__size-1, \@new_matrix);       
       } 
   return $m_det;
}
}                        # Line 40 
sub get_inverse ($\@)
{
my ($matrix_size, $m) =@_;
for ($i=0; $i<$matrix_size; $i++)
{
  for ($j=0; $j<$matrix_size; $j++)
  {
     $m5[$i][$j]=$$m[$i][$j];
     $mt[$i][$j]=$$m[$j][$i];
      }                  # Line 50  
}
for ($ii=0; $ii<$matrix_size; $ii++)
{
  for ($jj=0; $jj<$matrix_size; $jj++)
  {
     @aa=remove_row_col($ii,$jj,$matrix_size, @m5);             
     $inverse_matrix[$ii][$jj]=math_module::get_det($matrix_size-1, @aa) / math_module::get_det($matrix_size,@mt);
     $inverse_matrix[$ii][$jj]=((-1)**($ii+$jj+2))*$inverse_matrix[$ii][$jj];
  }
}                        # Line 60 
for ($ii=0; $ii<$matrix_size; $ii++)
{
  for ($jj=0; $jj<$matrix_size; $jj++)
  {
     $inverse_matrix1[$ii][$jj]=$inverse_matrix[$jj][$ii];
  }
}
return @inverse_matrix1;
}
sub remove_row_col ($$$@)
{
  my ($X_X, $Y_Y, $matrix_size, @matrix) =@_;
  
  for($i_i=0; $i_i < $matrix_size-1; $i_i++)
  {
    for($j_j=0; $j_j < $matrix_size; $j_j++)
    {
    if ($i_i < $X_X)
    {  
       $new_matrix[$i_i][$j_j]=$matrix[$i_i][$j_j];
    }
    if ($i_i >= $X_X)
    {  
       $new_matrix[$i_i][$j_j]=$matrix[$i_i+1][$j_j];
    }
  }
  }
  for($i_i=0; $i_i < $matrix_size-1; $i_i++)
  {
    for($j_j=0; $j_j < $matrix_size-1; $j_j++)
    {
    if ($j_j < $Y_Y)
    {  
       $new_matrix[$i_i][$j_j]=$new_matrix[$i_i][$j_j];
    }
    if ($j_j >= $Y_Y)
    {  
       $new_matrix[$i_i][$j_j]=$new_matrix[$i_i][$j_j+1];
    }
  }
  $new_matrix[$i_i][$matrix_size-1]="";  
  }   
  return @new_matrix;  
}
return 1;
##</code><code>##

C:\Users\x>cd desktop

C:\Users\x\Desktop>inv1.pl

 Here we intend to get the inverse of a 4x4 square matrix.

 Enter the Number of Rows i.e 4: 4

 The Inverse Matrix is:

-0.4  -1  0.8  0

1  1  -1  0

2.4  5  -2.8  -1

-2.2  -4  2.4  1
##</code><code>##

#!/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;
##</code><code>##

$m2[0]=[3,2,1,1]; 
$m2[1]=[1,0,2,2];
$m2[2]=[4,1,3,3];
$m2[3]=[1,2,3,4];

##</code><code>##

C:\Users\x>cd desktop

C:\Users\x\Desktop>inv2.pl

 Enter the Number of Rows i.e. 4 here: 4

 Please type the filename(.txt) i.e. d1.txt: d1.txt

 The contents of input matrix file are (array m2):

$m2[0]=[3,2,1,1];
 $m2[1]=[1,0,2,2];
 $m2[2]=[4,1,3,3];
 $m2[3]=[1,2,3,4];
Illegal division by zero at C:/Perl/lib/math_module.pm line 60, <DNAFILE>line 4.
##</code><code>##

3,2,1,1
1,0,2,2
4,1,3,3
1,2,3,4