For Aaron's case the expression is turned into
sin (Symbol )**(Integer (2 )('x' ))*Symbol ('x' )
For the original case the expression is turned into
Integer (10 )*sin (Symbol )**(Integer (120 )('x' ))*Symbol ('x' )**Integer
(2 )+Integer (3 )*Symbol ('x' )*Symbol ('y' )*Symbol ('z' )+tan (Symbol
('theta' ))
so the exponent/argument is not being properly captured. IIRC because this
works at the token level it only handles the case where the exponent is
something simple like just a symbol or integer, and not a product of
symbols and integers. This might make sense to reimplement as an AST
transformation instead, or otherwise the transformation would have to do
some actual parsing of the tokens.
David
On Thursday, February 19, 2015 at 10:35:21 PM UTC-5, Aaron Meurer wrote:
>
> A simpler example is sin**(2*x) x.
>
> Aaron Meurer
>
> On Thu, Feb 19, 2015 at 1:44 AM, Paul Royik <[email protected]
> <javascript:>> wrote:
> > Just noticed, that official example works:
> > from sympy.parsing.sympy_parser import (parse_expr,
> > standard_transformations, implicit_multiplication_application)
> > parse_expr("10sin**2 x**2 + 3xyz + tan
> > theta",transformations=(standard_transformations
> > +(implicit_multiplication_application,)))
> >
> > But
> > parse_expr("10sin**(120*x) x**2 + 3xyz + tan
> > theta",transformations=(standard_transformations
> > +(implicit_multiplication_application,)))
> > raises exception (see sine exponent):
> >
> > TypeError: unbound method could_extract_minus_sign() must be called with
> > Symbol instance as first argument (got nothing instead)
> >
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