You have to enable various transformers like implicit multiplication. See help(parse_expr)
Aaron Meurer On Wed, Oct 8, 2014 at 9:28 PM, <[email protected]> wrote: >>>> from sympy.parsing.sympy_parser import parse_expr >>>> parse_expr("(-6x^2-x-7)(2x^3+3x^2-2x-5)") > Traceback (most recent call last): > File "<pyshell#25>", line 1, in <module> > parse_expr("(-6x^2-x-7)(2x^3+3x^2-2x-5)") > File "C:\Python34\lib\site-packages\sympy\parsing\sympy_parser.py", line > 757, in parse_expr > return eval_expr(code, local_dict, global_dict) > File "C:\Python34\lib\site-packages\sympy\parsing\sympy_parser.py", line > 691, in eval_expr > code, global_dict, local_dict) # take local objects in preference > File "<string>", line 1 > (-Integer (6 )Symbol ('x' )^Integer (2 )-Symbol ('x' )-Integer (7 > ))(Integer (2 )Symbol ('x' )^Integer (3 )+Integer (3 )Symbol ('x' )^Integer > (2 )-Integer (2 )Symbol ('x' )-Integer (5 )) > ^ > SyntaxError: invalid syntax >>>> > > 在 2014年10月9日星期四UTC+8上午3时37分07秒，Aaron Meurer写道： >> >> Have a look at parse_expr() in sympy.parsing.sympy_parser. >> >> Aaron Meurer >> >> On Wed, Oct 8, 2014 at 8:42 AM, Mateusz Paprocki <[email protected]> wrote: >> > Hi, >> > >> > On 8 October 2014 12:05, <[email protected]> wrote: >> >> Is there any function in SymPy can take this TEX command as an input >> >> >> >> (-6x^2-x-7)(2x^3+3x^2-2x-5) >> >> >> >> to find the derivative? >> > >> > I wanted to suggest a mathematica parser for this: >> > >> > In [1]: import sympy.parsing.mathematica as m >> > >> > In [2]: m.parse("(-6x^2-x-7)(2x^3+3x^2-2x-5)") >> > Out[2]: '(-6*x**2-x-7)*(2*x**3+3*x**2-2*x-5)' >> > >> > In [3]: eval(_) >> > Out[3]: >> > ⎛ 2 ⎞ ⎛ 3 2 ⎞ >> > ⎝- 6⋅x - x - 7⎠⋅⎝2⋅x + 3⋅x - 2⋅x - 5⎠ >> > >> > But there is bug there and the above output requires the following >> > patch: >> > >> > diff --git a/sympy/parsing/mathematica.py b/sympy/parsing/mathematica.py >> > index f86d59a..eeb12f7 100644 >> > --- a/sympy/parsing/mathematica.py >> > +++ b/sympy/parsing/mathematica.py >> > @@ -39,7 +39,7 @@ def parse(s): >> > (r"\A\((.+)\)([\w\.].*)\Z", # Implied multiplication - (a)b >> > lambda m: "(" + parse(m.group(1)) + ")*" + parse(m.group(2))), >> > >> > - (r"\A([\d\.]+)([a-zA-Z].*)\Z", # Implied multiplicatin - 2a >> > + (r"\A([+-]?[\d\.]+)([a-zA-Z].*)\Z", # Implied multiplicatin - >> > 2a >> > lambda m: parse(m.group(1)) + "*" + parse(m.group(2))), >> > >> > (r"\A([^=]+)([\^\-\*/\+=]=?)(.+)\Z", # Infix operator >> > >> > Mateusz >> > >> >> -- >> >> You received this message because you are subscribed to the Google >> >> Groups >> >> "sympy" group. >> >> To unsubscribe from this group and stop receiving emails from it, send >> >> an >> >> email to [email protected]. >> >> To post to this group, send email to [email protected]. >> >> Visit this group at http://groups.google.com/group/sympy. >> >> To view this discussion on the web visit >> >> >> >> https://groups.google.com/d/msgid/sympy/04e0cbd4-5b6b-4418-8166-024a0729aff8%40googlegroups.com. >> >> For more options, visit https://groups.google.com/d/optout. >> > >> > -- >> > You received this message because you are subscribed to the Google >> > Groups "sympy" group. >> > To unsubscribe from this group and stop receiving emails from it, send >> > an email to [email protected]. >> > To post to this group, send email to [email protected]. >> > Visit this group at http://groups.google.com/group/sympy. >> > To view this discussion on the web visit >> > https://groups.google.com/d/msgid/sympy/CAGBZUCZfJVXw27Rh0U31ST9tU%3DwZbkuqUS792ff364JYvdG%2BHg%40mail.gmail.com. >> > For more options, visit https://groups.google.com/d/optout. > > -- > You received this message because you are subscribed to the Google Groups > "sympy" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > Visit this group at http://groups.google.com/group/sympy. > To view this discussion on the web visit > https://groups.google.com/d/msgid/sympy/2ca9f2ab-6070-4fe9-b896-131d5b36c53f%40googlegroups.com. > > For more options, visit https://groups.google.com/d/optout. -- You received this message because you are subscribed to the Google Groups "sympy" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/sympy. To view this discussion on the web visit https://groups.google.com/d/msgid/sympy/CAKgW%3D6LSP5--52qW8JCfJmXLJFvJceY3VVizwhMtF9B7FYLRag%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
