Method PowerToBezierMatrix

src/LNLib/Algorithm/Polynomials.cpp:622–657

}

std::vector<std::vector<double>> LNLib::Polynomials::PowerToBezierMatrix(int degree, const std::vector<std::vector<double>>& matrix)
{
	std::vector<std::vector<double>> inverseMatrix(degree + 1, std::vector<double>(degree + 1));
	for (int i = 0; i < degree; i++)
	{
		for (int j = i + 1; j <= degree; j++)
		{
			inverseMatrix[i][j] = 0.0;
		}
	}

	for (int i = 0; i <= degree; i++)
	{
		inverseMatrix[i][0] = inverseMatrix[degree][i] = 1.0;
		inverseMatrix[i][i] = 1.0 / (matrix[i][i]);
	}

	int k1 = (degree + 1) / 2;
	int pk = degree - 1;

	for (int k = 1; k < k1; k++)
	{
		for (int j = k + 1; j <= pk; j++)
		{
			double d = 0.0;
			for (int i = k; i < j; i++)
			{
				d = d - matrix[j][i] * inverseMatrix[i][k];
			}
			inverseMatrix[j][k] = d / (matrix[j][j]);
			inverseMatrix[pk][degree - j] = inverseMatrix[j][k];
		}
		pk = pk - 1;
	}
	return inverseMatrix;
}