On Tue, 2008-08-05 at 10:18 +0900, Marcio Braga wrote:
> simple code:
> 
> require 'matrix'
> m1 = Matrix[[1,2],[3,4]]
> 
> Now I need to change element (0,0) from 1 to 5. I expected something
> like the command below should work:
> 
> m1[0][0] = 5
> 
> ... but the error message is '[]': wrong number of arguments (1 for 2)
> (ArgumentError).
> 
> Could someone help me on that ?
> Thank you
> Marcio
IIRC a Matrix (and a Vector) is an immutable object -- you can't change
elements individually. You have to copy the Matrix to a
(two-dimensional) Array, change the Array element, and then convert the
Array back to a Matrix.

This is the only violation I've encountered of the rule that you can
write FORTRAN programs in any language. :)
-- 
M. Edward (Ed) Borasky
ruby-perspectives.blogspot.com

"A mathematician is a machine for turning coffee into theorems." --
Alfrƥd Rƥnyi via Paul Erd