assigning a value to x in diff(f(x),x)

Thanks! This looks promising.
is at(F(x,y),[x=0,y=0]) the same as F(0,0) when no derivatives are involved?

I still need to know which variables, if any, are involved in differential operators.
I now declare dependencies to deal with this (using atvalue, assuming all dependencies are involved in differentiation), but if somebody knows a more elegant method of finding the free dependent variables in an expression, please let me know.


Date: Fri, 6 Apr 2012 15:13:02 -0700
From: fateman at eecs.berkeley.edu
To: nijso at hotmail.com
Subject: Re: [Maxima] assigning a value to x in diff(f(x),x)


  


    
  
  
    try looking at   "at"

    

    On 4/6/2012 1:59 PM, nijso beishuizen wrote:
    
      
      
        Dear all,

        

        I have written a function separable(expr,x,y) that returns
        [f(x),g(y)] if expr is separable, and false otherwise.

        However, I have a problem with the exotic case where expr
        contains the derivative of an unknown function f(x), i.e. when
        expr:diff(f(x),x)*y

        The problem is that the algorithm works by assigning a value to
        x.

        

        Is there a way to make 'something like this' work:

        

        depends(f,x);

        define(F(x),diff(f,x));

        F(0);

        

        which should then result in the equivalent of  f '(0). 

        

        

        

      
      

      
      

      _______________________________________________
Maxima mailing list
Maxima at math.utexas.edu
http://www.math.utexas.edu/mailman/listinfo/maxima