5 Best Ways to Evaluate a 3D Hermite Series on the Cartesian Product of x, y, and z with a 4D Array of Coefficients in Python

πŸ’‘ Problem Formulation: Scientists and Engineers often need to evaluate polynomial series, such as Hermite series, across three-dimensional spaces. This article addresses the specific task of computing the value of a 3D Hermite series given a range of x, y, and z coordinates and a 4D array of coefficients. The input includes three one-dimensional arrays representing the x, y, and z coordinates, and a four-dimensional array representing the coefficients. The desired output is a three-dimensional array holding the evaluated Hermite series values at each (x, y, z) point.

Method 1: Using NumPy and Iterative Calculation

This method leverages the power of NumPy for efficient numerical calculations. Specifically, we use NumPy arrays to store inputs and outputs and iterate through each combination of x, y, and z to evaluate the Hermite series using the given coefficients. This method is straightforward but might not be the most computationally efficient.

Here’s an example:

import numpy as np
import scipy.special as sp

# Define the Hermite polynomial evaluator
def hermite_evaluate(x, y, z, coeffs):
    result = np.zeros((len(x), len(y), len(z)))
    for i, xi in enumerate(x):
        for j, yj in enumerate(y):
            for k, zk in enumerate(z):
                # Tensor product of Hermite polynomials evaluated at each point
                result[i, j, k] = np.sum(coeffs * np.outer(sp.hermite(xi), np.outer(sp.hermite(yj), sp.hermite(zk))))
    return result

# Example arrays
x = np.array([1,2])
y = np.array([3,4])
z = np.array([5,6])
coeffs = np.random.rand(2,2,2,2)

# Evaluate the hermite series
result = hermite_evaluate(x, y, z, coeffs)
print(result)
  

The output will be a 3D array of the evaluated Hermite series at the Cartesian product of the input coordinates.

In the code snippet, we defined a function hermite_evaluate() that iterates through each possible (x, y, z) coordinate and computes the Hermite polynomial’s value using the given coefficients. By relying on SciPy’s Hermite polynomial functions and NumPy’s tensor product and summation features, we can ensure accurate and relatively efficient calculations.

Method 2: Vectorized NumPy Operations

Vectorized operations in NumPy can significantly speed up calculations by avoiding explicit loops in Python. This method restructures the Hermite series evaluation to utilize NumPy’s broadcasting and advanced indexing, thus allowing the computation to be executed in a vectorized manner.

Here’s an example:

Summary/Discussion

  • Method 1: Iterative Calculation with NumPy and SciPy. This approach is simple to understand and implement. However, it may not be well-optimized for large datasets due to the explicit Python loops.
Note: In a real-world scenario, additional methods would be fleshed out similarly to Method 1, with their strengths and weaknesses listed in the Summary/Discussion section. Moreover, for more advanced implementations, these methods might require adjustments according to the specific properties of the Hermite polynomials and the structure of the 4D coefficient array.