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 | 1 | initial version |
There is no need to define such a function.
No need for var('n i') either, by the way.
Once you have defined the function g by
sage: g(x) = sin(x) + tan(x)
you can check that g is a function, and g(x) is the corresponding expression:
sage: g
x |--> sin(x) + tan(x)
sage: g(x)
sin(x) + tan(x)
and then you can differentiate the function or the expression three times.
The only thing is that the variable with respect to which to differentiate must be specified.
sage: g.diff(x, 3)
x |--> 4*(tan(x)^2 + 1)*tan(x)^2 + 2*(tan(x)^2 + 1)^2 - cos(x)
sage: g(x).diff(x, 3)
4*(tan(x)^2 + 1)*tan(x)^2 + 2*(tan(x)^2 + 1)^2 - cos(x)
| | 2 | No.2 Revision |
There is no need to define such a function.
No need for var('n i') either, by the way.
Once you have defined the function g by
sage: g(x) = sin(x) + tan(x)
you can check that g is a function, and g(x) is the corresponding expression:
sage: g
x |--> sin(x) + tan(x)
sage: g(x)
sin(x) + tan(x)
and then you can differentiate the function or the expression three times.
The only thing is that the variable with respect to which to differentiate must be specified.
sage: g.diff(x, 3)
x |--> 4*(tan(x)^2 + 1)*tan(x)^2 + 2*(tan(x)^2 + 1)^2 - cos(x)
sage: g(x).diff(x, 3)
4*(tan(x)^2 + 1)*tan(x)^2 + 2*(tan(x)^2 + 1)^2 - cos(x)
If however you want to understand the error you were getting, here is a hint.
When you do g = g.diff() inside a function, it wants to use a local variable g
inside the function.
If you want to use a globally defined variable, specify it with global g as follows:
sage: def maderive(n):
....: global g
....: for i in range(n):
....: g=g.diff()
....: return g
....:
sage: maderive(3)
x |--> 4*(tan(x)^2 + 1)*tan(x)^2 + 2*(tan(x)^2 + 1)^2 - cos(x)
Note that this modifies the function g. After running the above, you get:
sage: g
x |--> 4*(tan(x)^2 + 1)*tan(x)^2 + 2*(tan(x)^2 + 1)^2 - cos(x)
