public AffineTransformMatrix3D inverse()

in commons-geometry-euclidean/src/main/java/org/apache/commons/geometry/euclidean/threed/AffineTransformMatrix3D.java [435:485]
36 lines of code
1 McCabe index (conditional complexity)

    public AffineTransformMatrix3D inverse() {

        // Our full matrix is 4x4 but we can significantly reduce the amount of computations
        // needed here since we know that our last row is [0 0 0 1].

        final double det = Matrices.checkDeterminantForInverse(determinant());

        // validate the remaining matrix elements that were not part of the determinant
        Matrices.checkElementForInverse(m03);
        Matrices.checkElementForInverse(m13);
        Matrices.checkElementForInverse(m23);

        // compute the necessary elements of the cofactor matrix
        // (we need all but the last column)

        final double invDet = 1.0 / det;

        final double c00 = invDet * Matrices.determinant(m11, m12, m21, m22);
        final double c01 = -invDet * Matrices.determinant(m10, m12, m20, m22);
        final double c02 = invDet * Matrices.determinant(m10, m11, m20, m21);

        final double c10 = -invDet * Matrices.determinant(m01, m02, m21, m22);
        final double c11 = invDet * Matrices.determinant(m00, m02, m20, m22);
        final double c12 = -invDet * Matrices.determinant(m00, m01, m20, m21);

        final double c20 = invDet * Matrices.determinant(m01, m02, m11, m12);
        final double c21 = -invDet * Matrices.determinant(m00, m02, m10, m12);
        final double c22 = invDet * Matrices.determinant(m00, m01, m10, m11);

        final double c30 = -invDet * Matrices.determinant(
                    m01, m02, m03,
                    m11, m12, m13,
                    m21, m22, m23
                );
        final double c31 = invDet * Matrices.determinant(
                    m00, m02, m03,
                    m10, m12, m13,
                    m20, m22, m23
                );
        final double c32 = -invDet * Matrices.determinant(
                    m00, m01, m03,
                    m10, m11, m13,
                    m20, m21, m23
                );

        return new AffineTransformMatrix3D(
                    c00, c10, c20, c30,
                    c01, c11, c21, c31,
                    c02, c12, c22, c32
                );
    }