在 Python 中使用复数点数组生成切比雪夫多项式的范德蒙矩阵


要生成切比雪夫多项式的范德蒙矩阵,请在 Python Numpy 中使用 chebyshev.chebvander()。该方法返回范德蒙矩阵。返回矩阵的形状为 x.shape + (deg + 1,),其中最后一个索引是相应切比雪夫多项式的次数。dtype 将与转换后的 x 相同。

参数 a 是点数组。dtype 会根据是否有任何元素为复数而转换为 float64 或 complex128。如果 x 是标量,则将其转换为一维数组。参数 deg 是结果矩阵的次数。

步骤

首先,导入所需的库 -

import numpy as np
from numpy.polynomial import chebyshev as C

创建数组 -

x = np.array([-2.+2.j, -1.+2.j, 0.+2.j, 1.+2.j, 2.+2.j])

显示数组 -

print("Our Array...\n",x)

检查维度 -

print("\nDimensions of our Array...\n",x.ndim)

获取数据类型 -

print("\nDatatype of our Array object...\n",x.dtype)

获取形状 -

print("\nShape of our Array object...\n",x.shape)

要生成切比雪夫多项式的范德蒙矩阵,请使用 chebyshev.chebvander() -

print("\nResult...\n",C.chebvander(x, 2))

示例

import numpy as np
from numpy.polynomial import chebyshev as C

# Create an array
x = np.array([-2.+2.j, -1.+2.j, 0.+2.j, 1.+2.j, 2.+2.j])

# Display the array
print("Our Array...\n",x)

# Check the Dimensions
print("\nDimensions of our Array...\n",x.ndim)

# Get the Datatype
print("\nDatatype of our Array object...\n",x.dtype)

# Get the Shape
print("\nShape of our Array object...\n",x.shape)

# To generate a Vandermonde matrix of the Chebyshev polynomial, use the chebyshev.chebvander() in Python Numpy
# The method returns the Vandermonde matrix. The shape of the returned matrix is x.shape + (deg + 1,), where The last index is the degree of the corresponding Chebyshev polynomial. The dtype will be the same as the converted x.
# The parameter, a is Array of points. The dtype is converted to float64 or complex128 depending on whether any of the elements are complex. If x is scalar it is converted to a 1-D array.
# The parameter, deg is the degree of the resulting matrix
print("\nResult...\n",C.chebvander(x, 2))

输出

Our Array...
[-2.+2.j -1.+2.j 0.+2.j 1.+2.j 2.+2.j]

Dimensions of our Array...
1

Datatype of our Array object...
complex128

Shape of our Array object...
(5,)

Result...
[[ 1. +0.j -2. +2.j -1.-16.j]
[ 1. +0.j -1. +2.j -7. -8.j]
[ 1. +0.j 0. +2.j -9. +0.j]
[ 1. +0.j 1. +2.j -7. +8.j]
[ 1. +0.j 2. +2.j -1.+16.j]]

更新于: 2022年2月28日

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