Task

Build an   identity matrix   of a size known at run-time.



An identity matrix is a square matrix of size n × n,

where the diagonal elements are all 1s (ones),

and all the other elements are all 0s (zeroes).







I

n


=


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1


0


0


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0




0


1


0


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0




0


0


1


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0




⋮


⋮


⋮


⋱


⋮




0


0


0


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1



]




{\displaystyle I_{n}={\begin{bmatrix}1&0&0&\cdots &0\\0&1&0&\cdots &0\\0&0&1&\cdots &0\\\vdots &\vdots &\vdots &\ddots &\vdots \\0&0&0&\cdots &1\\\end{bmatrix}}}





Related tasks

   Spiral matrix
   Zig-zag matrix 
   Ulam_spiral_(for_primes)


use strict;
use warnings;
use feature 'say';
 
sub identity_matrix {
    my($n) = shift() - 1;
    map { [ (0) x $_, 1, (0) x ($n - $_) ] } 0..$n
}
 
for (<4 5 6>) {
  say "\n$_:";
  say join ' ', @$_ for identity_matrix $_;
}