/*
 * Copyright 2011-2013 JOptimizer
 *
 *   Licensed under the Apache License, Version 2.0 (the "License");
 *   you may not use this file except in compliance with the License.
 *   You may obtain a copy of the License at
 *
 *       http://www.apache.org/licenses/LICENSE-2.0
 *
 *   Unless required by applicable law or agreed to in writing, software
 *   distributed under the License is distributed on an "AS IS" BASIS,
 *   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *   See the License for the specific language governing permissions and
 *   limitations under the License.
 */
package com.joptimizer.functions;

import com.joptimizer.util.Utils;

import cern.colt.matrix.DoubleFactory1D;
import cern.colt.matrix.DoubleFactory2D;
import cern.colt.matrix.DoubleMatrix1D;
import cern.colt.matrix.DoubleMatrix2D;
import cern.colt.matrix.linalg.Algebra;
import cern.jet.math.Functions;
import cern.jet.math.Mult;

/**
 * Default barrier function for the barrier method algorithm.
 * 
If f_i(x) are the inequalities of the problem, theh we have:
 * 
Φ = - Sum_i[log(-f_i(x))]
 * @see "S.Boyd and L.Vandenberghe, Convex Optimization, 11.2.1"
 * @author alberto trivellato (alberto.trivellato@gmail.com)
 */
public class LogarithmicBarrier implements BarrierFunction {

	final Algebra ALG = Algebra.DEFAULT;
	final DoubleFactory1D F1 = DoubleFactory1D.dense;
	final DoubleFactory2D F2 = DoubleFactory2D.dense;
	private ConvexMultivariateRealFunction[] fi = null;
	private int dim = -1;

	/**
	 * Create the logarithmic barrier function.
	 * @see "S.Boyd and L.Vandenberghe, Convex Optimization, 11.2.1"
	 */
	public LogarithmicBarrier(ConvexMultivariateRealFunction[] fi, int dim) {
		this.fi = fi;
		this.dim = dim;
	}

	public double value(double[] X) {
		double psi = 0;
		for(int j=0; j=0){
				return Double.NaN;
			}
			psi -= Math.log(-ineqValuejX);
		}
		return psi;
	}

	public double[] gradient(double[] X) {
		DoubleMatrix1D gradFiSum = F1.make(getDim());
		for(int j=0; jfi(X)-s, i=1,...,n
	 */
	public BarrierFunction createPhase1BarrierFunction(){
		
		final int dimPh1 = dim +1;
		ConvexMultivariateRealFunction[] inequalitiesPh1 = new ConvexMultivariateRealFunction[this.fi.length];
		for(int i=0; i