在不反转系数的情况下使用 poly1d polyder 对多项式求导

Question

我正在使用 poly1d 和 polyder 来 return 简单多项式的导数。

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

我发现这两个命令的简单组合并没有以正确的顺序使用系数。

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

有没有一个我可以像这样使用的衬垫

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

以便上面的系数顺序正确？

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

对从 np.poly1d 返回的对象使用 deriv 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。

在不反转系数的情况下使用 poly1d polyder 对多项式求导

taking derivative of a polynomial using poly1d polyder without reversing the coefficients

python

arrays

numpy

polynomials