On Thu, 9 Jun 2005, Keean Schupke wrote:
Henning Thielemann wrote:
MatLab must provide these automatisms because it doesn't have proper higher functions. I think the Haskell way is to provide a 'map' for matrices. Otherwise the question is: What is the most natural 'exp' on matrices? The elementwise application of 'exp' to each element or the matrix exponentation?
MatLab has "exp" which works element wise and "expm" which does the matrix-exponentation.
This would be the worsed possible mix - just in the spirit of MatLab. :-) With (*) meaning a matrix multiplication and 'exp' meaning elementwise exponentation, the exponential law exp (x+y) = exp x * exp y does not hold. For elementwise (*) operation it would hold and for 'exp' as matrix exponentation it would hold at least for matrices x and y which are diagonalisable by the same similarity transform.