// Prototype for Wolfe condition test
#include "SteepestDescent.h"

float 	DotProduct(Vec x, Vec y){
	int i;
	float sum=0.0;
	
	for(i=0;i<x.n;i++){
		sum+=x.comp[i]*y.comp[i];
		}
	return sum;
	}
	
int 	WolfeTest(
	const Vec x, 
	const float alpha, 
	const Vec p, 
	const float fval, 
	const Vec gradfval,
	float (*F)(const Vec x),
	Vec (*GradF)(const Vec x)
	){
	float fNew, c1=0.001, c2=0.9;
	int i, test1, test2 = 0;
	Vec xNew, gradfNew;
	
	xNew.n = x.n;
	xNew.comp = (float *) malloc(x.n * sizeof(float));
	for(i=0; i< x.n; i++){
		xNew.comp[i] = x.comp[i] + alpha*p.comp[i];
		}
	fNew = F(xNew);
	test1 = (
		fNew < fval + c1*alpha*DotProduct(p, gradfval)
		);
	if(test1){
		gradfNew = GradF(xNew);
		test2 = (
			DotProduct(p, gradfNew) > c2*DotProduct(p, gradfval)
			);
			}
	return test2;
	}