If you let g be a tuple of expressions involving t you can use the Python * operator to use the tuple entries as your inputs x, y, and z:
sage: g = (t, t^2, t^3)
sage: f = lambda x,y,z: (2*x, y+x+z, y*x)
sage: f(*g)
(2*t, t^3 + t^2 + t, t^3)
If you want to define both g and f as lambda functions you could do:
sage: g = lambda t: (t, t^2, t^3)
sage: f = lambda x,y,z: (2*x, y+x+z, y*x)
sage: f(*g(t))
(2*t, t^3 + t^2 + t, t^3)
You don't need f to be a lambda function for this; using "f(x,y,z) = (2*x,y+x+z,y*x)" works just fine.
Thank you for the alternative. For the moment it looks like non-lambda functions work well. I'm not well versed in python and I'd like to make things look as much like mathematical notation as possible. Also, it seems using other properties (methods, functions?) like jacobian and derivative is more straight forward if lambda functions are avoided.
h(t) = f(*g(t))
But it might be nice to have this work without that. See http://trac.sagemath.org/sage_trac/ticket/11180; if someone can come up with a better title for that ticket, be my guest.
Asked: 2011-04-09 19:32:57 +0100
Seen: 2,723 times
Last updated: Apr 09 '11
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