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Сергей Александров
Asked:2020-11-05 21:56:57 +0000 UTC2020-11-05 21:56:57 +0000 UTC

如何在简化中插入变量

  • 772

a111=200

我想插入此变量，但出现错误

  formula = "a111+(x-0.2)0.9823456+(x-0.235)(x-0.2145)(-0.976123)"

从 sympy 导入简化

from sympy.parsing.sympy_parser import (
        parse_expr,
        standard_transformations,
        implicit_application,
        implicit_multiplication,
        implicit_multiplication_application,
        function_exponentiation)

transformations=(standard_transformations +
                 (implicit_multiplication,
                  implicit_application,
                  function_exponentiation,
                  ))

formula = "0.88522+(x-0.2)0.9823456+(x-0.235)(x-0.2145)(-0.976123)"
expr = parse_expr(formula,transformations=transformations)
simplified_formula = simplify(expr)
print(simplified_formula)
python

1 个回答

  1. Best Answer

    例子：

    In [103]: from sympy import symbols

In [104]: a111 = symbols("a111")

In [105]: formula = "a111+(x-0.2)0.9823456+(x-0.235)(x-0.2145)(-0.976123)"

In [106]: expr = parse_expr(formula,transformations=transformations)

In [107]: simplified_formula = simplify(expr)

In [108]: simplified_formula
Out[108]: 1.0*a111 - 0.976123*x**2 + 1.4211128885*x - 0.2456730401225

In [109]: simplified_formula.subs(dict(a111=200))
Out[109]: -0.976123*x**2 + 1.4211128885*x + 199.754326959877

    您可以替换变量的值并简化：

    In [110]: expr = parse_expr(formula,transformations=transformations).subs({"a111":200})
#  NOTE:              --------------------------------------------> ^^^^^^^^^^^^^^^^^^^

In [111]: expr
Out[111]: 0.9823456*x - 0.976123*(x - 0.235)*(x - 0.2145) + 199.80353088

In [112]: simplify(expr)
Out[112]: -0.976123*x**2 + 1.4211128885*x + 199.754326959878
    • 2

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