identity matrix

Identity matrix

=i

Given a positive integer argument n, identity matrix returns a n×n matrix with ones in the main diagonal and zeros elsewhere.

Try it!

 =5
(1 0 0 0 0
 0 1 0 0 0
 0 0 1 0 0
 0 0 0 1 0
 0 0 0 0 1)

 =1
,,1

 =0
()

Works in: ngn/k

This primitive is not available in all dialects. There are multiple ways to implement it in K:

 im:{t=/:t:!x}
 im[4]
(1 0 0 0
 0 1 0 0
 0 0 1 0
 0 0 0 1)

 im:{(2#x)#1,&x}
 im[2]
(1 0
 0 1)

 im:{(x-1)(0 :':)\~!x}   / fast
 im[3]
(1 0 0
 0 1 0
 0 0 1)