ASKSAGE: Sage Q&A Forum - Latest question feedhttp://ask.sagemath.org/questions/Q&A Forum for SageenCopyright Sage, 2010. Some rights reserved under creative commons license.Thu, 16 Jan 2014 01:18:05 -0600Calculus with formal functions: substitution?http://ask.sagemath.org/question/10928/calculus-with-formal-functions-substitution/If I enter
var('f,x,y')
y = function('y',x)
f = function('f',x,y)
then
f.diff(x)
returns
D[1](f)(x, y(x))*D[0](y)(x) + D[0](f)(x, y(x))
In order to perform more computations later on, I want to rewrite this, using substitutions, so it looks something like
Fy*yx + Fx
But I've got no idea how to do this. In Maxima I'd just use `'diff(f,x)` as the expression to substitute for, but even trying to use `dummy_diff` doesn't seem to work:
from sage.calculus.calculus import dummy_diff
dummy_diff(f,x)
produces the same result as `f.diff(x)` above.
Does anybody know how I can use substitutions to express the results of a formal differentiation with other symbols?AlasdairThu, 16 Jan 2014 01:18:05 -0600http://ask.sagemath.org/question/10928/