no.uib.cipr.matrix.AbstractVector Maven / Gradle / Ivy
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/*
* Copyright (C) 2003-2006 Bjørn-Ove Heimsund
*
* This file is part of MTJ.
*
* This library is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as published by the
* Free Software Foundation; either version 2.1 of the License, or (at your
* option) any later version.
*
* This library is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
* for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this library; if not, write to the Free Software Foundation,
* Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
package no.uib.cipr.matrix;
import java.io.Serializable;
import java.util.Formatter;
import java.util.Iterator;
/**
* Partial implementation of Vector. The following methods throw
* UnsupportedOperationException, and should be overridden by a
* subclass:
*
* get(int)set(int,double)copy
*
* For the rest of the methods, simple default implementations using a vector
* iterator has been provided. There are some kernel operations which the
* simpler operations forward to, and they are:
*
* -
add(double,Vector) and set(double,Vector).
* -
scale(double).
* dot(Vector) and all the norms.
*
* Finally, a default iterator is provided by this class, which works by calling
* the get function. A tailored replacement should be used by
* subclasses.
*/
public abstract class AbstractVector implements Vector, Serializable {
/**
* Size of the vector
*/
protected int size;
/**
* Constructor for AbstractVector.
*
* @param size
* Size of the vector
*/
protected AbstractVector(int size) {
if (size < 0)
throw new IllegalArgumentException("Vector size cannot be negative");
this.size = size;
}
/**
* Constructor for AbstractVector, same size as x
*
* @param x
* Vector to get the size from
*/
protected AbstractVector(Vector x) {
this.size = x.size();
}
public int size() {
return size;
}
public void set(int index, double value) {
throw new UnsupportedOperationException();
}
public void add(int index, double value) {
set(index, value + get(index));
}
public double get(int index) {
throw new UnsupportedOperationException();
}
public Vector copy() {
throw new UnsupportedOperationException();
}
/**
* Checks the index is non-zero and within the vector
*/
protected void check(int index) {
if (index < 0)
throw new IndexOutOfBoundsException("index is negative (" + index
+ ")");
if (index >= size)
throw new IndexOutOfBoundsException("index >= size (" + index
+ " >= " + size + ")");
}
public Vector zero() {
for (VectorEntry e : this)
e.set(0);
return this;
}
public Vector scale(double alpha) {
if (alpha == 0)
return zero();
else if (alpha == 1)
return this;
for (VectorEntry e : this)
e.set(alpha * e.get());
return this;
}
public Vector set(Vector y) {
return set(1, y);
}
public Vector set(double alpha, Vector y) {
checkSize(y);
if (alpha == 0)
return zero();
zero();
for (VectorEntry e : y)
set(e.index(), alpha * e.get());
return this;
}
public Vector add(Vector y) {
return add(1, y);
}
public Vector add(double alpha, Vector y) {
checkSize(y);
if (alpha == 0)
return this;
for (VectorEntry e : y)
add(e.index(), alpha * e.get());
return this;
}
public double dot(Vector y) {
checkSize(y);
double ret = 0;
for (VectorEntry e : this)
ret += e.get() * y.get(e.index());
return ret;
}
/**
* Checks for conformant sizes
*/
protected void checkSize(Vector y) {
if (size != y.size())
throw new IndexOutOfBoundsException("x.size != y.size (" + size
+ " != " + y.size() + ")");
}
public double norm(Norm type) {
if (type == Norm.One)
return norm1();
else if (type == Norm.Two)
return norm2();
else if (type == Norm.TwoRobust)
return norm2_robust();
else
// Infinity
return normInf();
}
protected double norm1() {
double sum = 0;
for (VectorEntry e : this)
sum += Math.abs(e.get());
return sum;
}
protected double norm2() {
double norm = 0;
for (VectorEntry e : this)
norm += e.get() * e.get();
return Math.sqrt(norm);
}
protected double norm2_robust() {
double scale = 0, ssq = 1;
for (VectorEntry e : this) {
double xval = e.get();
if (xval != 0) {
double absxi = Math.abs(xval);
if (scale < absxi) {
ssq = 1 + ssq * Math.pow(scale / absxi, 2);
scale = absxi;
} else
ssq = ssq + Math.pow(absxi / scale, 2);
}
}
return scale * Math.sqrt(ssq);
}
protected double normInf() {
double max = 0;
for (VectorEntry e : this)
max = Math.max(Math.abs(e.get()), max);
return max;
}
public Iterator iterator() {
return new RefVectorIterator();
}
@Override
public String toString() {
// Output into coordinate format. Indices start from 1 instead of 0
Formatter out = new Formatter();
out.format("%10d %19d\n", size, Matrices.cardinality(this));
int i = 0;
for (VectorEntry e : this) {
if (e.get() != 0)
out.format("%10d % .12e\n", e.index() + 1, e.get());
if (++i == 100) {
out.format("...\n");
break;
}
}
return out.toString();
}
/**
* Iterator over a general vector
*/
private class RefVectorIterator implements Iterator {
private int index;
private final RefVectorEntry entry = new RefVectorEntry();
public boolean hasNext() {
return index < size;
}
public VectorEntry next() {
entry.update(index);
index++;
return entry;
}
public void remove() {
entry.set(0);
}
}
/**
* Vector entry backed by the vector. May be reused for higher performance
*/
private class RefVectorEntry implements VectorEntry {
private int index;
/**
* Updates the entry
*/
public void update(int index) {
this.index = index;
}
public int index() {
return index;
}
public double get() {
return AbstractVector.this.get(index);
}
public void set(double value) {
AbstractVector.this.set(index, value);
}
}
}