using System;
public static partial class matlib{

public static (vector,matrix) lsfit(
	Func<double,double>[] fs, vector x, vector y, vector dy){
	int n = x.size, m=fs.Length;
	var A = new matrix(n,m);
	var b = new vector(n);
	for(int i=0;i<n;i++){
		b[i]=y[i]/dy[i];
		for(int k=0;k<m;k++)A[i,k]=fs[k](x[i])/dy[i];
		}
	var qra = new GSQR(A);
	vector c = qra.solve(b);
	matrix invA = qra.pinverse();
	matrix S = invA*invA.T;
//	var invR = (new GSQR(qra.R)).inverse();
//	var S = invR*invR.T;
	return (c,S);
	}//lsfit

}//class