Just Another Victim of the Ambient Morality wrote:
> "M. Edward (Ed) Borasky" <znmeb / cesmail.net> wrote
>> You can only set an arbitrary element of a Matrix when it is created.
>> Once created, you can't change any of the entries.
> 
>     The []= operator does seem conspicuously missing.  If anyone knows why 
> this was (obviously) deliberately left out, please say something!

It's by design. A Matrix is immutable, like Ruby's other numbers
(Fixnum, Rational, Complex...)

Consider subclassing rather than modifying the base class for this reason.

class MutableMatrix < Matrix
  def []= ...

Cheers,
Dave