Source code for skysegmentor.maths

import numpy as np




def vector_norm(a: np.ndarray) -> float:
    """Returns the magnitude a vector.

    Parameters
    ----------
    a : array
        Vector a.
    """
    a1, a2, a3 = a[0], a[1], a[2]
    return np.sqrt(a1**2.0 + a2**2.0 + a3**2.0)





def vector_dot(a: np.ndarray, b: np.ndarray) -> float:
    """Returns the vector dot product.

    Parameters
    ----------
    a : array
        Vector a.
    b : array
        Vector b.
    """
    a1, a2, a3 = a[0], a[1], a[2]
    b1, b2, b3 = b[0], b[1], b[2]
    return a1 * b1 + a2 * b2 + a3 * b3





def vector_cross(a: np.ndarray, b: np.ndarray) -> np.ndarray:
    """Returns the vector cross product.

    Parameters
    ----------
    a : array
        Vector a.
    b : array
        Vector b.

    Returns
    -------
    s : array
        Cross product vector.
    """
    a1, a2, a3 = a[0], a[1], a[2]
    b1, b2, b3 = b[0], b[1], b[2]
    s1 = a2 * b3 - a3 * b2
    s2 = a3 * b1 - a1 * b3
    s3 = a1 * b2 - a2 * b1
    s = np.array([s1, s2, s3])
    return s





def matrix_dot_3by3(mat1: np.ndarray, mat2: np.ndarray) -> np.ndarray:
    """Dot product of 2 3x3 matrices.

    Parameters
    ----------
    mat1, mat2 : array
        Flattened 3by3 matrices.

    Returns
    -------
    mat3 : array
        Matrix dot product output.
    """
    mat3 = np.array(
        [
            mat1[0] * mat2[0] + mat1[1] * mat2[3] + mat1[2] * mat2[6],
            mat1[0] * mat2[1] + mat1[1] * mat2[4] + mat1[2] * mat2[7],
            mat1[0] * mat2[2] + mat1[1] * mat2[5] + mat1[2] * mat2[8],
            mat1[3] * mat2[0] + mat1[4] * mat2[3] + mat1[5] * mat2[6],
            mat1[3] * mat2[1] + mat1[4] * mat2[4] + mat1[5] * mat2[7],
            mat1[3] * mat2[2] + mat1[4] * mat2[5] + mat1[5] * mat2[8],
            mat1[6] * mat2[0] + mat1[7] * mat2[3] + mat1[8] * mat2[6],
            mat1[6] * mat2[1] + mat1[7] * mat2[4] + mat1[8] * mat2[7],
            mat1[6] * mat2[2] + mat1[7] * mat2[5] + mat1[8] * mat2[8],
        ]
    )
    return mat3