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


=


[



1


0


0


⋯


0




0


1


0


⋯


0




0


0


1


⋯


0




⋮


⋮


⋮


⋱


⋮




0


0


0


⋯


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)


S" fsl-util.fs" REQUIRED
 
: build-identity ( 'p n -- 'p )  \ make an NxN identity matrix
  0 DO
    I 1+ 0 DO
      I J = IF  1.0E0 DUP I J }} F!
      ELSE
        0.0E0 DUP J I }} F!
        0.0E0 DUP I J }} F!
      THEN
    LOOP
  LOOP ;
 
6 6 float matrix a{{
a{{ 6 build-identity
6 6 a{{ }}fprint