[R] symbolic matrix elements...

[Evan Cooch]

Eik Vettorazzi wrote:
> test=matrix(c( expression(x^3-5*x+4), expression(log(x^2-4*x))))
> works.
Well, not really (or I'm misunderstanding). Your code enters fine (no 
errors), but I can't access individual elements - e.g., test[1,1] gives 
me an error:

 > test=matrix(c( expression(x^3-5*x+4), expression(log(x^2-4*x))))
 > test[1,1]
Error: matrix subscripting not handled for this type

Meaning...what?

>
> btw. you recieved an error because D expects an expression and you 
> offered a list

OK - so why then are each of the elements identified as an expression 
which I print out the vector? Each element is reported to be an 
expression. OK, if so, then I remain puzzled as to how this is a 'list'.