On Sun, Mar 03, 2002 at 12:11:13AM +0900, Yukihiro Matsumoto wrote: > I asked Keiju, who has been my friend for long time, and he replied > that that's because he wanted matrix to be immutable just like other > numeric values. Hmm, I see a matrix as more of a two-dimensional array with arithmetic operators redefined for matrix operations. If an array is mutable, a matrix should be mutable, too. (if you need further convincing, consider the performance implications of constructing a new matrix just to change a single cell). Paul