我有一个编写多项式函数的python程序,然后使用Sympy的 solve()
函数来查找它们的反转 .
x = Symbol('x')
y = Symbol('y')
for i in range(10):
p = Poly.create_random()
print("p orig " + str(p))
solve(p, x)
print("p in terms of x: " + str(p))
solve(p, y)
print("p in terms of y (inverse): " + str(p))
但是,当我运行该程序时,我收到以下错误:
p orig y = 5*x**2 - 55*x**1 + 140
Traceback (most recent call last):
File "/usr/local/lib/python3.5/dist-packages/sympy/core/sympify.py", line 354, in sympify
expr = parse_expr(a, local_dict=locals, transformations=transformations, evaluate=evaluate)
File "/usr/local/lib/python3.5/dist-packages/sympy/parsing/sympy_parser.py", line 894, in parse_expr
return eval_expr(code, local_dict, global_dict)
File "/usr/local/lib/python3.5/dist-packages/sympy/parsing/sympy_parser.py", line 807, in eval_expr
code, global_dict, local_dict) # take local objects in preference
File "<string>", line 1
Symbol ('y' )=Integer (5 )*Symbol ('x' )**Integer (2 )-Integer (55 )*Symbol ('x' )**Integer (1 )+Integer (140 )
^
SyntaxError: invalid syntax
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "z.py", line 110, in <module>
solve(p, x)
File "/usr/local/lib/python3.5/dist-packages/sympy/solvers/solvers.py", line 833, in solve
f, symbols = (_sympified_list(w) for w in [f, symbols])
File "/usr/local/lib/python3.5/dist-packages/sympy/solvers/solvers.py", line 833, in <genexpr>
f, symbols = (_sympified_list(w) for w in [f, symbols])
File "/usr/local/lib/python3.5/dist-packages/sympy/solvers/solvers.py", line 824, in _sympified_list
return list(map(sympify, w if iterable(w) else [w]))
File "/usr/local/lib/python3.5/dist-packages/sympy/core/sympify.py", line 356, in sympify
raise SympifyError('could not parse %r' % a, exc)
sympy.core.sympify.SympifyError: Sympify of expression 'could not parse 'y = 5*x**2 - 55*x**1 + 140'' failed, because of exception being raised:
SyntaxError: invalid syntax (<string>, line 1)
对于Sympy,您必须使用 **
编写指数,并将乘法符号编写为 *
. 除此之外,我不太确定Sympy的具体语法 .
1 回答
我认为你需要用符号x和y来定义多项式 .
solve
假设多项式等于零,因此从中减去y,如下所示 . 在Python 3.5.2中:给出这个结果: