//	Header file matvec.hh ( --> matvec.cc)

//	matvec.hh

//		Print vector
void PrintVec(const int n, const double x[]);

//		Read dimension from file, allocate vector, 
//				read vector components from file
void ConstructVector(const char filename[], int & n, double * & vec);

//		Print matrix
void PrintMat(const int nrow, const int ncol, const double a[]);

//		Read dimensions from file, allocate matrix, 
//				read matrix components from file
void ConstructMatrix(const char filename[], 
			int & nrow, int & ncol, double * & mat);

//	Matrix times vector product
void MatMul(const int nrow, const int ncol, 
  	      const double a[], const double u[], double erg[]);

//######################################################################
//	remaining functions need to be implemented

//	Get vector of diagonal entries from matrix
//		(the vector is already allocated)
void GetMatrixDiag(const int nrow, const int ncol, const double a[], 
			double diag[]);

//	Calculate defect (defect vector is already allocated)
void GetDefect(const int nrow, const int ncol, const double a[], 
		const double f[], const double u[], double defect[]);

//	Calculate L2-norm of a vector
double L2norm(const int n, const double vec[]);

//		Print vector to file
void PrintVec2File(const int n, const double x[], const char name[]);