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)


 
include "NSLog.incl"
 
local fn IdentityMatrix( n as NSInteger ) as CFStringRef
NSInteger i, j
CFMutableArrayRef tempArr = fn MutableArrayWithCapacity( n )
CFMutableStringRef mutStr = fn MutableStringWithCapacity( 0 )
 
for i = 0 to n - 1
MutableArrayRemoveAllObjects( tempArr )
for j = 0 to n - 1
MutableArrayInsertObjectAtIndex( tempArr, @"0", j )
next
MutableArrayReplaceObjectAtIndex( tempArr, @"1", i )
MutableStringAppendString( mutStr, fn ArrayComponentsJoinedByString( tempArr, @" " ) )
MutableStringAppendString( mutStr, @"\n" )
next
end fn = fn StringWithString( mutStr )
 
NSLog( @"3:\n%@", fn IdentityMatrix( 3 ) )
NSLog( @"5:\n%@", fn IdentityMatrix( 5 ) )
NSLog( @"7:\n%@", fn IdentityMatrix( 7 ) )
NSLog( @"9:\n%@", fn IdentityMatrix( 9 ) )
 
HandleEvents
 