spline.cpp

void computeCubicSplineCoefficients(double** a, double* x, double* y, int n)
{
	double** matrix = new double*[n-1];
	for (int i=0; i<n-1; i++)
		matrix[i] = new double[n-1];
	double* sol = new double[n-1];
	double* rhs = new double[n-1];

	//create our h array
	double* h = new double[n-1];
	

	for(int i=0;i<n-1;++i)
	{
		h[i] =  x[i+1]-x[i];
		std::cout << h[i] << std::endl;
	}

	//fill the matrix here
	for(int i=0;i<n-1;++i)
	{	
		if(i-1>=0)
			matrix[i][i-1]=h[i+1];
		matrix[i][i]= 2*(h[i+1]+h[i+2]);
		if(i+1<=n+1)
			matrix[i][i+1]=h[i+2];

		rhs[i] = 3*((y[i+2]-y[i+1])/h[i+1]-(y[i+1]-y[i])/h[i]);
	}

	for(int r=0;r<n-1;++r)
	{
		for(int c=0;c<n-1;++c)
			std::cout << matrix[r][c] << "\t";
		std::cout << std::endl;
	}
	
	// solve
	solveByGaussSeidel(sol, matrix, rhs, n-1);
	for(int i=0;i<n-1;++i)
	{
		std::cout << sol[i]<< std::endl;
	}
		



	// cleanup
	for (int i=0; i<n-1; i++)
		delete [] matrix[i];
	delete []  matrix;
	delete [] sol;
	delete [] rhs;
}