You could make a function "factory", right?
def rfunc(name):
rv = Function(name)
rv.is_real = True
return rv
>>> f = rfunc('f')
>>> f(var('x')).is_real
True
On Tuesday, February 24, 2015 at 5:33:20 PM UTC-6, Aaron Meurer wrote:
>
> It looks like
>
> f = Function('f')
> f.is_real = True
>
> also works, although I wouldn't use it unless you really don't know
> the names of the functions you want to create until runtime.
>
> Aaron Meurer
>
>
> On Tue, Feb 24, 2015 at 5:31 PM, Aaron Meurer <[email protected]
> <javascript:>> wrote:
> > On Tue, Feb 24, 2015 at 4:51 PM, John Peterson <[email protected]
> <javascript:>> wrote:
> >>
> >>
> >> On Tuesday, February 24, 2015 at 3:15:03 PM UTC-7, Aaron Meurer wrote:
> >>>
> >>> The problem is that assumptions on Function don't do anything
> >>> (https://github.com/sympy/sympy/issues/6494). If you want to create a
> >>> Function with assumptions, you'll need to subclass Function
> >>> explicitly, like
> >>>
> >>> class f(Function):
> >>> is_real = True
> >>
> >>
> >> Thanks for pointing out the real issue! I tried to implement your
> >> suggestion, but I'm not a particularly skillful python programmer, so
> my
> >> first attempt at subclassing Function in the way you described didn't
> >> work...
> >>
> >> Here's the code:
> >>
> >>> #!/usr/bin/env python
> >>> from sympy import *
> >>> class real_function(Function):
> >>> is_real=True
> >>> X = Symbol('X', real=True)
> >>> f = real_function('f')(X)
> >>> g = real_function('g')(X)
> >>> print diff (abs(f-g), X)
> >
> > It would just be real_function(X).
> >
> > "Function('f')" is (roughly) the same as "class f(Function): pass".
> > That is, it creates a subclass of Function called f. You will need to
> > create a new subclass for each function. Clearly, that's not super
> > easy to do if you want to create them on the fly, which is why we
> > should fix that issue.
> >
> > Aaron Meurer
> >
> >>
> >>
> >> And the error message:
> >>
> >>> Traceback (most recent call last):
> >>> File "testcase.py", line 10, in <module>
> >>> f = real_function('f')(X)
> >>> TypeError: 'real_function' object is not callable
> >>
> >>
> >> which I don't understand how to fix.
> >>
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