Aaron S. Meurer wrote:
Wouldn't you just use the .subs() method, or does that not work?

Aaron Meurer
On Jun 13, 2010, at 6:57 AM, Alan Bromborsky wrote:

How would I do the following:

I have a generic function:  d_1 = Function('d_1')(x)

that I apply to another function f in an expression such as y = 5*x_1**2+d_1(f).

Later I wish to substitute an explicit function such as

def D_1(f):
  return(diff(f,x_1))

for d_1 and have y expanded after the substitution.  For example if f = 
x_1**2+x_2**2 then
y = 5*x_1**2+2*x_1



--
You received this message because you are subscribed to the Google Groups 
"sympy" group.
To post to this group, send email to [email protected].
To unsubscribe from this group, send email to 
[email protected].
For more options, visit this group at 
http://groups.google.com/group/sympy?hl=en.


I tried this:

from sympy import *

x = Symbol('x')
x_1 = Symbol('x_1')
x_2 = Symbol('x_2')

def df_1(F):
   global x_1
   return(diff(F,x_1))


if __name__ == '__main__':

   F = Function('df')(x)

   y = x_1**2+x_2**2

   z = y+F(y)

   print z


and got:

Traceback (most recent call last):
 File "testtensor.py", line 26, in <module>
   z = y+F(y)
File "/usr/local/lib/python2.6/dist-packages/sympy-0.6.7_git-py2.6.egg/sympy/core/basic.py", line 1310, in __call__
   raise TypeError("argument must be a dictionary")
TypeError: argument must be a dictionary

I must be missing something.  I haven't even tried to substitute yet.

--
You received this message because you are subscribed to the Google Groups 
"sympy" group.
To post to this group, send email to [email protected].
To unsubscribe from this group, send email to 
[email protected].
For more options, visit this group at 
http://groups.google.com/group/sympy?hl=en.

Reply via email to