quote:
cause math don''t like ifs and elses (or have you seen them yet in formulas in school?)
Yes, the Kronecker Delta:
d(ij) = { (1, if i=j), (0, if i!=j) }
Can be used to specify things even as simple as your identity matrix (and things much more complex).
http://mathworld.wolfram.com/KroneckerDelta.html