using System;
using static System.Math;
using static System.Console;
public class ann2{

public Func<double,double> f  = z => Exp(-z*z)*z;
public Func<double,double> f1 = z => Exp(-z*z)*(1-2*z*z);
public Func<double,double> f2 = z => Exp(-z*z)*(-4*z-2*z+4*z*z*z);
public vector p;
public readonly int n;
public double a(int i) { return(p[i]); }
public double b(int i) { return(p[i+n]); }
public double w(int i) { return(p[i+2*n]); }
public void seta(int i,double z) { p[i]=z; }
public void setb(int i,double z) { p[i+n]=z; }
public void setw(int i,double z) { p[i+2*n]=z; }

public ann2(int n){ this.n=n; p=new vector(3*n); }
public ann2(vector p){ this.n=p.size/3; this.p=p; }

public double func(double x){
	double sum=0;
	for(int i=0;i<n;i++) sum+=w(i)*f((x-a(i))/b(i));
	return sum;
	}

public double deriv1(double x){
	double sum=0;
	for(int i=0;i<n;i++) sum+=w(i)*f1((x-a(i))/b(i)/b(i));
	return sum;
	}

public double deriv2(double x){
	double sum=0;
	for(int i=0;i<n;i++) sum+=w(i)*f2((x-a(i))/b(i)/b(i)/b(i));
	return sum;
	}

public void train(Func<ann2,double> cost){
	Random rnd=new Random();
	for(int i=0;i<n;i++){
		setw(i,1);
		setb(i,1);
		seta(i,rnd.NextDouble());
	}
	int ncalls=0;
	Func<vector,double> mismatch = (u) => {
		ncalls++;
		ann2 annu = new ann2(u);
		return cost(annu);
		};
	double step=0.7;
	simplex.downhill(mismatch,ref p,step:step,sizegoal:1e-6);
	//qnewton.min(mismatch,ref p,acc:1e-3,method:"broyden");
//vector lcorner=p.copy(); for(int i=0;i<lcorner.size;i++) lcorner[i]-=step;
//vector rcorner=p.copy(); for(int i=0;i<rcorner.size;i++) rcorner[i]+=step;
//p=rndstart.run(mismatch,lcorner,rcorner,seconds:1,acc:1e-4);
//p=prernd.run(mismatch,lcorner,rcorner,seconds:1,acc:1e-4);
Error.Write($"ncalls={ncalls}\n");
	}

}//network