Question

我使用poly1d和polyder来返回简单多项式的导数。

   3     2
1 x + 1 x + 1 x + 1

我看到这两个命令的简单组合并没有以正确的顺序使用这些系数。

print(np.poly1d(P.polyder(c)))

我可以像这样使用一个班轮

print(np.poly1d(P.polyder(c)))

以便上述系数的顺序正确吗？

Below is my code and output:

    import numpy as np
from numpy.polynomial import polynomial as P

print("")

c = (1, 1, 1, 1)

print("the array of coefficients for the polynomial")
print(c)

print("")

print("polynomial with coefficients and exponents")
print(np.poly1d(c))

print("")

print("array of coefficients of derivative of polynomial: lowest order coming first in the array")
d_c = P.polyder(c)
print(d_c)

print("")

print("reversing the array of coefficients for the derivative of the polynomial")
d_c = d_c[::-1]
print(d_c)

print("")

print("printing the derivative of the polynomial with exponents and coefficients")
print(np.poly1d(d_c))

print("")

print("printing the derivative of the polynomial without reversing the coefficient array after derivation")
print(np.poly1d(P.polyder(c)))

print("")

输出：

the array of coefficients for the polynomial
(1, 1, 1, 1)

polynomial with coefficients and exponents
   3     2
1 x + 1 x + 1 x + 1

array of coefficients of derivative of polynomial: lowest order coming first in the array
[ 1.  2.  3.]

reversing the array of coefficients for the derivative of the polynomial
[ 3.  2.  1.]

printing the derivative of the polynomial with exponents and coefficients
   2
3 x + 2 x + 1

printing the derivative of the polynomial without reversing the coefficient array after derivation
   2
1 x + 2 x + 3

Answer 1

对deriv上的对象使用np.poly1d方法：

import numpy as np

p = np.poly1d([1, 3, 1, 0, 4])

print(p)
print(p.deriv(1))

有关可用方法的完整列表，请参阅the docs。

使用poly1d多边形取多项式的导数而不反转系数

1 个答案: