/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 org.apache.commons.math3.linear;

import java.io.Serializable;
import java.util.Arrays;
import java.util.Iterator;

import org.apache.commons.math3.analysis.UnivariateFunction;
import org.apache.commons.math3.exception.NotPositiveException;
import org.apache.commons.math3.exception.NullArgumentException;
import org.apache.commons.math3.exception.DimensionMismatchException;
import org.apache.commons.math3.exception.NumberIsTooLargeException;
import org.apache.commons.math3.exception.NumberIsTooSmallException;
import org.apache.commons.math3.exception.OutOfRangeException;
import org.apache.commons.math3.exception.util.LocalizedFormats;
import org.apache.commons.math3.util.MathUtils;
import org.apache.commons.math3.util.FastMath;

This class implements the RealVector interface with a double array. 
Since:
2.0/**
 * This class implements the {@link RealVector} interface with a double array.
 * @since 2.0
 */
public class ArrayRealVector extends RealVector implements Serializable {
    
Serializable version identifier. /** Serializable version identifier. */
    private static final long serialVersionUID = -1097961340710804027L;
    
Default format. /** Default format. */
    private static final RealVectorFormat DEFAULT_FORMAT = RealVectorFormat.getInstance();

    
Entries of the vector. /** Entries of the vector. */
    private double data[];

    
Build a 0-length vector. Zero-length vectors may be used to initialized construction of vectors by data gathering. We start with zero-length and use either the ArrayRealVector(ArrayRealVector, ArrayRealVector) constructor or one of the append method (append(double), append(ArrayRealVector)) to gather data into this vector. /**
     * Build a 0-length vector.
     * Zero-length vectors may be used to initialized construction of vectors
     * by data gathering. We start with zero-length and use either the {@link
     * #ArrayRealVector(ArrayRealVector, ArrayRealVector)} constructor
     * or one of the {@code append} method ({@link #append(double)},
     * {@link #append(ArrayRealVector)}) to gather data into this vector.
     */
    public ArrayRealVector() {
        data = new double[0];
    }

    
Construct a vector of zeroes.
Params:
size – Size of the vector./**
     * Construct a vector of zeroes.
     *
     * @param size Size of the vector.
     */
    public ArrayRealVector(int size) {
        data = new double[size];
    }

    
Construct a vector with preset values.
Params:
size – Size of the vector
preset – All entries will be set with this value./**
     * Construct a vector with preset values.
     *
     * @param size Size of the vector
     * @param preset All entries will be set with this value.
     */
    public ArrayRealVector(int size, double preset) {
        data = new double[size];
        Arrays.fill(data, preset);
    }

    
Construct a vector from an array, copying the input array.
Params:
d – Array./**
     * Construct a vector from an array, copying the input array.
     *
     * @param d Array.
     */
    public ArrayRealVector(double[] d) {
        data = d.clone();
    }

    
Create a new ArrayRealVector using the input array as the underlying data array. If an array is built specially in order to be embedded in a ArrayRealVector and not used directly, the copyArray may be set to false. This will prevent the copying and improve performance as no new array will be built and no data will be copied. 
Params:
d – Data for the new vector.
copyArray – if true, the input array will be copied, otherwise it will be referenced.
Throws:
NullArgumentException – if d is null.
See Also:
ArrayRealVector(double[])/**
     * Create a new ArrayRealVector using the input array as the underlying
     * data array.
     * If an array is built specially in order to be embedded in a
     * ArrayRealVector and not used directly, the {@code copyArray} may be
     * set to {@code false}. This will prevent the copying and improve
     * performance as no new array will be built and no data will be copied.
     *
     * @param d Data for the new vector.
     * @param copyArray if {@code true}, the input array will be copied,
     * otherwise it will be referenced.
     * @throws NullArgumentException if {@code d} is {@code null}.
     * @see #ArrayRealVector(double[])
     */
    public ArrayRealVector(double[] d, boolean copyArray)
        throws NullArgumentException {
        if (d == null) {
            throw new NullArgumentException();
        }
        data = copyArray ? d.clone() :  d;
    }

    
Construct a vector from part of a array.
Params:
d – Array.
pos – Position of first entry.
size – Number of entries to copy.
Throws:
NullArgumentException – if d is null.
NumberIsTooLargeException – if the size of d is less than pos + size./**
     * Construct a vector from part of a array.
     *
     * @param d Array.
     * @param pos Position of first entry.
     * @param size Number of entries to copy.
     * @throws NullArgumentException if {@code d} is {@code null}.
     * @throws NumberIsTooLargeException if the size of {@code d} is less
     * than {@code pos + size}.
     */
    public ArrayRealVector(double[] d, int pos, int size)
        throws NullArgumentException, NumberIsTooLargeException {
        if (d == null) {
            throw new NullArgumentException();
        }
        if (d.length < pos + size) {
            throw new NumberIsTooLargeException(pos + size, d.length, true);
        }
        data = new double[size];
        System.arraycopy(d, pos, data, 0, size);
    }

    
Construct a vector from an array.
Params:
d – Array of Doubles./**
     * Construct a vector from an array.
     *
     * @param d Array of {@code Double}s.
     */
    public ArrayRealVector(Double[] d) {
        data = new double[d.length];
        for (int i = 0; i < d.length; i++) {
            data[i] = d[i].doubleValue();
        }
    }

    
Construct a vector from part of an array.
Params:
d – Array.
pos – Position of first entry.
size – Number of entries to copy.
Throws:
NullArgumentException – if d is null.
NumberIsTooLargeException – if the size of d is less than pos + size./**
     * Construct a vector from part of an array.
     *
     * @param d Array.
     * @param pos Position of first entry.
     * @param size Number of entries to copy.
     * @throws NullArgumentException if {@code d} is {@code null}.
     * @throws NumberIsTooLargeException if the size of {@code d} is less
     * than {@code pos + size}.
     */
    public ArrayRealVector(Double[] d, int pos, int size)
        throws NullArgumentException, NumberIsTooLargeException {
        if (d == null) {
            throw new NullArgumentException();
        }
        if (d.length < pos + size) {
            throw new NumberIsTooLargeException(pos + size, d.length, true);
        }
        data = new double[size];
        for (int i = pos; i < pos + size; i++) {
            data[i - pos] = d[i].doubleValue();
        }
    }

    
Construct a vector from another vector, using a deep copy.
Params:
v – vector to copy.
Throws:
NullArgumentException – if v is null./**
     * Construct a vector from another vector, using a deep copy.
     *
     * @param v vector to copy.
     * @throws NullArgumentException if {@code v} is {@code null}.
     */
    public ArrayRealVector(RealVector v) throws NullArgumentException {
        if (v == null) {
            throw new NullArgumentException();
        }
        data = new double[v.getDimension()];
        for (int i = 0; i < data.length; ++i) {
            data[i] = v.getEntry(i);
        }
    }

    
Construct a vector from another vector, using a deep copy.
Params:
v – Vector to copy.
Throws:
NullArgumentException – if v is null./**
     * Construct a vector from another vector, using a deep copy.
     *
     * @param v Vector to copy.
     * @throws NullArgumentException if {@code v} is {@code null}.
     */
    public ArrayRealVector(ArrayRealVector v) throws NullArgumentException {
        this(v, true);
    }

    
Construct a vector from another vector.
Params:
v – Vector to copy.
deep – If true perform a deep copy, otherwise perform a shallow copy./**
     * Construct a vector from another vector.
     *
     * @param v Vector to copy.
     * @param deep If {@code true} perform a deep copy, otherwise perform a
     * shallow copy.
     */
    public ArrayRealVector(ArrayRealVector v, boolean deep) {
        data = deep ? v.data.clone() : v.data;
    }

    
Construct a vector by appending one vector to another vector.
Params:
v1 – First vector (will be put in front of the new vector).
v2 – Second vector (will be put at back of the new vector)./**
     * Construct a vector by appending one vector to another vector.
     * @param v1 First vector (will be put in front of the new vector).
     * @param v2 Second vector (will be put at back of the new vector).
     */
    public ArrayRealVector(ArrayRealVector v1, ArrayRealVector v2) {
        data = new double[v1.data.length + v2.data.length];
        System.arraycopy(v1.data, 0, data, 0, v1.data.length);
        System.arraycopy(v2.data, 0, data, v1.data.length, v2.data.length);
    }

    
Construct a vector by appending one vector to another vector.
Params:
v1 – First vector (will be put in front of the new vector).
v2 – Second vector (will be put at back of the new vector)./**
     * Construct a vector by appending one vector to another vector.
     * @param v1 First vector (will be put in front of the new vector).
     * @param v2 Second vector (will be put at back of the new vector).
     */
    public ArrayRealVector(ArrayRealVector v1, RealVector v2) {
        final int l1 = v1.data.length;
        final int l2 = v2.getDimension();
        data = new double[l1 + l2];
        System.arraycopy(v1.data, 0, data, 0, l1);
        for (int i = 0; i < l2; ++i) {
            data[l1 + i] = v2.getEntry(i);
        }
    }

    
Construct a vector by appending one vector to another vector.
Params:
v1 – First vector (will be put in front of the new vector).
v2 – Second vector (will be put at back of the new vector)./**
     * Construct a vector by appending one vector to another vector.
     * @param v1 First vector (will be put in front of the new vector).
     * @param v2 Second vector (will be put at back of the new vector).
     */
    public ArrayRealVector(RealVector v1, ArrayRealVector v2) {
        final int l1 = v1.getDimension();
        final int l2 = v2.data.length;
        data = new double[l1 + l2];
        for (int i = 0; i < l1; ++i) {
            data[i] = v1.getEntry(i);
        }
        System.arraycopy(v2.data, 0, data, l1, l2);
    }

    
Construct a vector by appending one vector to another vector.
Params:
v1 – First vector (will be put in front of the new vector).
v2 – Second vector (will be put at back of the new vector)./**
     * Construct a vector by appending one vector to another vector.
     * @param v1 First vector (will be put in front of the new vector).
     * @param v2 Second vector (will be put at back of the new vector).
     */
    public ArrayRealVector(ArrayRealVector v1, double[] v2) {
        final int l1 = v1.getDimension();
        final int l2 = v2.length;
        data = new double[l1 + l2];
        System.arraycopy(v1.data, 0, data, 0, l1);
        System.arraycopy(v2, 0, data, l1, l2);
    }

    
Construct a vector by appending one vector to another vector.
Params:
v1 – First vector (will be put in front of the new vector).
v2 – Second vector (will be put at back of the new vector)./**
     * Construct a vector by appending one vector to another vector.
     * @param v1 First vector (will be put in front of the new vector).
     * @param v2 Second vector (will be put at back of the new vector).
     */
    public ArrayRealVector(double[] v1, ArrayRealVector v2) {
        final int l1 = v1.length;
        final int l2 = v2.getDimension();
        data = new double[l1 + l2];
        System.arraycopy(v1, 0, data, 0, l1);
        System.arraycopy(v2.data, 0, data, l1, l2);
    }

    
Construct a vector by appending one vector to another vector.
Params:
v1 – first vector (will be put in front of the new vector)
v2 – second vector (will be put at back of the new vector)/**
     * Construct a vector by appending one vector to another vector.
     * @param v1 first vector (will be put in front of the new vector)
     * @param v2 second vector (will be put at back of the new vector)
     */
    public ArrayRealVector(double[] v1, double[] v2) {
        final int l1 = v1.length;
        final int l2 = v2.length;
        data = new double[l1 + l2];
        System.arraycopy(v1, 0, data, 0, l1);
        System.arraycopy(v2, 0, data, l1, l2);
    }

    
{@inheritDoc} /** {@inheritDoc} */
    @Override
    public ArrayRealVector copy() {
        return new ArrayRealVector(this, true);
    }

    
{@inheritDoc} /** {@inheritDoc} */
    @Override
    public ArrayRealVector add(RealVector v)
        throws DimensionMismatchException {
        if (v instanceof ArrayRealVector) {
            final double[] vData = ((ArrayRealVector) v).data;
            final int dim = vData.length;
            checkVectorDimensions(dim);
            ArrayRealVector result = new ArrayRealVector(dim);
            double[] resultData = result.data;
            for (int i = 0; i < dim; i++) {
                resultData[i] = data[i] + vData[i];
            }
            return result;
        } else {
            checkVectorDimensions(v);
            double[] out = data.clone();
            Iterator<Entry> it = v.iterator();
            while (it.hasNext()) {
                final Entry e = it.next();
                out[e.getIndex()] += e.getValue();
            }
            return new ArrayRealVector(out, false);
        }
    }

    
{@inheritDoc} /** {@inheritDoc} */
    @Override
    public ArrayRealVector subtract(RealVector v)
        throws DimensionMismatchException {
        if (v instanceof ArrayRealVector) {
            final double[] vData = ((ArrayRealVector) v).data;
            final int dim = vData.length;
            checkVectorDimensions(dim);
            ArrayRealVector result = new ArrayRealVector(dim);
            double[] resultData = result.data;
            for (int i = 0; i < dim; i++) {
                resultData[i] = data[i] - vData[i];
            }
            return result;
        } else {
            checkVectorDimensions(v);
            double[] out = data.clone();
            Iterator<Entry> it = v.iterator();
            while (it.hasNext()) {
                final Entry e = it.next();
                out[e.getIndex()] -= e.getValue();
            }
            return new ArrayRealVector(out, false);
        }
    }

    
{@inheritDoc} /** {@inheritDoc} */
    @Override
    public ArrayRealVector map(UnivariateFunction function) {
        return copy().mapToSelf(function);
    }

    
{@inheritDoc} /** {@inheritDoc} */
    @Override
    public ArrayRealVector mapToSelf(UnivariateFunction function) {
        for (int i = 0; i < data.length; i++) {
            data[i] = function.value(data[i]);
        }
        return this;
    }

    
{@inheritDoc} /** {@inheritDoc} */
    @Override
    public RealVector mapAddToSelf(double d) {
        for (int i = 0; i < data.length; i++) {
            data[i] += d;
        }
        return this;
    }

    
{@inheritDoc} /** {@inheritDoc} */
    @Override
    public RealVector mapSubtractToSelf(double d) {
        for (int i = 0; i < data.length; i++) {
            data[i] -= d;
        }
        return this;
    }

    
{@inheritDoc} /** {@inheritDoc} */
    @Override
    public RealVector mapMultiplyToSelf(double d) {
        for (int i = 0; i < data.length; i++) {
            data[i] *= d;
        }
        return this;
    }

    
{@inheritDoc} /** {@inheritDoc} */
    @Override
    public RealVector mapDivideToSelf(double d) {
        for (int i = 0; i < data.length; i++) {
            data[i] /= d;
        }
        return this;
    }

    
{@inheritDoc} /** {@inheritDoc} */
    @Override
    public ArrayRealVector ebeMultiply(RealVector v)
        throws DimensionMismatchException {
        if (v instanceof ArrayRealVector) {
            final double[] vData = ((ArrayRealVector) v).data;
            final int dim = vData.length;
            checkVectorDimensions(dim);
            ArrayRealVector result = new ArrayRealVector(dim);
            double[] resultData = result.data;
            for (int i = 0; i < dim; i++) {
                resultData[i] = data[i] * vData[i];
            }
            return result;
        } else {
            checkVectorDimensions(v);
            double[] out = data.clone();
            for (int i = 0; i < data.length; i++) {
                out[i] *= v.getEntry(i);
            }
            return new ArrayRealVector(out, false);
        }
    }

    
{@inheritDoc} /** {@inheritDoc} */
    @Override
    public ArrayRealVector ebeDivide(RealVector v)
        throws DimensionMismatchException {
        if (v instanceof ArrayRealVector) {
            final double[] vData = ((ArrayRealVector) v).data;
            final int dim = vData.length;
            checkVectorDimensions(dim);
            ArrayRealVector result = new ArrayRealVector(dim);
            double[] resultData = result.data;
            for (int i = 0; i < dim; i++) {
                resultData[i] = data[i] / vData[i];
            }
            return result;
        } else {
            checkVectorDimensions(v);
            double[] out = data.clone();
            for (int i = 0; i < data.length; i++) {
                out[i] /= v.getEntry(i);
            }
            return new ArrayRealVector(out, false);
        }
    }

    
Get a reference to the underlying data array.
This method does not make a fresh copy of the underlying data.
Returns:
the array of entries./**
     * Get a reference to the underlying data array.
     * This method does not make a fresh copy of the underlying data.
     *
     * @return the array of entries.
     */
    public double[] getDataRef() {
        return data;
    }

    
{@inheritDoc} /** {@inheritDoc} */
    @Override
    public double dotProduct(RealVector v) throws DimensionMismatchException {
        if (v instanceof ArrayRealVector) {
            final double[] vData = ((ArrayRealVector) v).data;
            checkVectorDimensions(vData.length);
            double dot = 0;
            for (int i = 0; i < data.length; i++) {
                dot += data[i] * vData[i];
            }
            return dot;
        }
        return super.dotProduct(v);
    }

    
{@inheritDoc} /** {@inheritDoc} */
    @Override
    public double getNorm() {
        double sum = 0;
        for (double a : data) {
            sum += a * a;
        }
        return FastMath.sqrt(sum);
    }

    
{@inheritDoc} /** {@inheritDoc} */
    @Override
    public double getL1Norm() {
        double sum = 0;
        for (double a : data) {
            sum += FastMath.abs(a);
        }
        return sum;
    }

    
{@inheritDoc} /** {@inheritDoc} */
    @Override
    public double getLInfNorm() {
        double max = 0;
        for (double a : data) {
            max = FastMath.max(max, FastMath.abs(a));
        }
        return max;
    }

    
{@inheritDoc} /** {@inheritDoc} */
    @Override
    public double getDistance(RealVector v) throws DimensionMismatchException {
        if (v instanceof ArrayRealVector) {
            final double[] vData = ((ArrayRealVector) v).data;
            checkVectorDimensions(vData.length);
            double sum = 0;
            for (int i = 0; i < data.length; ++i) {
                final double delta = data[i] - vData[i];
                sum += delta * delta;
            }
            return FastMath.sqrt(sum);
        } else {
            checkVectorDimensions(v);
            double sum = 0;
            for (int i = 0; i < data.length; ++i) {
                final double delta = data[i] - v.getEntry(i);
                sum += delta * delta;
            }
            return FastMath.sqrt(sum);
        }
    }

    
{@inheritDoc} /** {@inheritDoc} */
    @Override
    public double getL1Distance(RealVector v)
        throws DimensionMismatchException {
        if (v instanceof ArrayRealVector) {
            final double[] vData = ((ArrayRealVector) v).data;
            checkVectorDimensions(vData.length);
            double sum = 0;
            for (int i = 0; i < data.length; ++i) {
                final double delta = data[i] - vData[i];
                sum += FastMath.abs(delta);
            }
            return sum;
        } else {
            checkVectorDimensions(v);
            double sum = 0;
            for (int i = 0; i < data.length; ++i) {
                final double delta = data[i] - v.getEntry(i);
                sum += FastMath.abs(delta);
            }
            return sum;
        }
    }

    
{@inheritDoc} /** {@inheritDoc} */
    @Override
    public double getLInfDistance(RealVector v)
        throws DimensionMismatchException {
        if (v instanceof ArrayRealVector) {
            final double[] vData = ((ArrayRealVector) v).data;
            checkVectorDimensions(vData.length);
            double max = 0;
            for (int i = 0; i < data.length; ++i) {
                final double delta = data[i] - vData[i];
                max = FastMath.max(max, FastMath.abs(delta));
            }
            return max;
        } else {
            checkVectorDimensions(v);
            double max = 0;
            for (int i = 0; i < data.length; ++i) {
                final double delta = data[i] - v.getEntry(i);
                max = FastMath.max(max, FastMath.abs(delta));
            }
            return max;
        }
    }

    
{@inheritDoc} /** {@inheritDoc} */
    @Override
    public RealMatrix outerProduct(RealVector v) {
        if (v instanceof ArrayRealVector) {
            final double[] vData = ((ArrayRealVector) v).data;
            final int m = data.length;
            final int n = vData.length;
            final RealMatrix out = MatrixUtils.createRealMatrix(m, n);
            for (int i = 0; i < m; i++) {
                for (int j = 0; j < n; j++) {
                    out.setEntry(i, j, data[i] * vData[j]);
                }
            }
            return out;
        } else {
            final int m = data.length;
            final int n = v.getDimension();
            final RealMatrix out = MatrixUtils.createRealMatrix(m, n);
            for (int i = 0; i < m; i++) {
                for (int j = 0; j < n; j++) {
                    out.setEntry(i, j, data[i] * v.getEntry(j));
                }
            }
            return out;
        }
    }

    
{@inheritDoc} /** {@inheritDoc} */
    @Override
    public double getEntry(int index) throws OutOfRangeException {
        try {
            return data[index];
        } catch (IndexOutOfBoundsException e) {
            throw new OutOfRangeException(LocalizedFormats.INDEX, index, 0,
                getDimension() - 1);
        }
    }

    
{@inheritDoc} /** {@inheritDoc} */
    @Override
    public int getDimension() {
        return data.length;
    }

    
{@inheritDoc} /** {@inheritDoc} */
    @Override
    public RealVector append(RealVector v) {
        try {
            return new ArrayRealVector(this, (ArrayRealVector) v);
        } catch (ClassCastException cce) {
            return new ArrayRealVector(this, v);
        }
    }

    
Construct a vector by appending a vector to this vector.
Params:
v – Vector to append to this one.
Returns:
a new vector./**
     * Construct a vector by appending a vector to this vector.
     *
     * @param v Vector to append to this one.
     * @return a new vector.
     */
    public ArrayRealVector append(ArrayRealVector v) {
        return new ArrayRealVector(this, v);
    }

    
{@inheritDoc} /** {@inheritDoc} */
    @Override
    public RealVector append(double in) {
        final double[] out = new double[data.length + 1];
        System.arraycopy(data, 0, out, 0, data.length);
        out[data.length] = in;
        return new ArrayRealVector(out, false);
    }

    
{@inheritDoc} /** {@inheritDoc} */
    @Override
    public RealVector getSubVector(int index, int n)
        throws OutOfRangeException, NotPositiveException {
        if (n < 0) {
            throw new NotPositiveException(LocalizedFormats.NUMBER_OF_ELEMENTS_SHOULD_BE_POSITIVE, n);
        }
        ArrayRealVector out = new ArrayRealVector(n);
        try {
            System.arraycopy(data, index, out.data, 0, n);
        } catch (IndexOutOfBoundsException e) {
            checkIndex(index);
            checkIndex(index + n - 1);
        }
        return out;
    }

    
{@inheritDoc} /** {@inheritDoc} */
    @Override
    public void setEntry(int index, double value) throws OutOfRangeException {
        try {
            data[index] = value;
        } catch (IndexOutOfBoundsException e) {
            checkIndex(index);
        }
    }

    
{@inheritDoc} /** {@inheritDoc} */
    @Override
    public void addToEntry(int index, double increment)
        throws OutOfRangeException {
        try {
        data[index] += increment;
        } catch(IndexOutOfBoundsException e){
            throw new OutOfRangeException(LocalizedFormats.INDEX,
                                          index, 0, data.length - 1);
        }
    }

    
{@inheritDoc} /** {@inheritDoc} */
    @Override
    public void setSubVector(int index, RealVector v)
        throws OutOfRangeException {
        if (v instanceof ArrayRealVector) {
            setSubVector(index, ((ArrayRealVector) v).data);
        } else {
            try {
                for (int i = index; i < index + v.getDimension(); ++i) {
                    data[i] = v.getEntry(i - index);
                }
            } catch (IndexOutOfBoundsException e) {
                checkIndex(index);
                checkIndex(index + v.getDimension() - 1);
            }
        }
    }

    
Set a set of consecutive elements.
Params:
index – Index of first element to be set.
v – Vector containing the values to set.
Throws:
OutOfRangeException – if the index is inconsistent with the vector
size./**
     * Set a set of consecutive elements.
     *
     * @param index Index of first element to be set.
     * @param v Vector containing the values to set.
     * @throws OutOfRangeException if the index is inconsistent with the vector
     * size.
     */
    public void setSubVector(int index, double[] v)
        throws OutOfRangeException {
        try {
            System.arraycopy(v, 0, data, index, v.length);
        } catch (IndexOutOfBoundsException e) {
            checkIndex(index);
            checkIndex(index + v.length - 1);
        }
    }

    
{@inheritDoc} /** {@inheritDoc} */
    @Override
    public void set(double value) {
        Arrays.fill(data, value);
    }

    
{@inheritDoc} /** {@inheritDoc} */
    @Override
    public double[] toArray(){
        return data.clone();
    }

    
{@inheritDoc} /** {@inheritDoc} */
    @Override
    public String toString(){
        return DEFAULT_FORMAT.format(this);
    }

    
Check if instance and specified vectors have the same dimension.
Params:
v – Vector to compare instance with.
Throws:
DimensionMismatchException – if the vectors do not
have the same dimension./**
     * Check if instance and specified vectors have the same dimension.
     *
     * @param v Vector to compare instance with.
     * @throws DimensionMismatchException if the vectors do not
     * have the same dimension.
     */
    @Override
    protected void checkVectorDimensions(RealVector v)
        throws DimensionMismatchException {
        checkVectorDimensions(v.getDimension());
    }

    
Check if instance dimension is equal to some expected value.
Params:
n – Expected dimension.
Throws:
DimensionMismatchException – if the dimension is
inconsistent with vector size./**
     * Check if instance dimension is equal to some expected value.
     *
     * @param n Expected dimension.
     * @throws DimensionMismatchException if the dimension is
     * inconsistent with vector size.
     */
    @Override
    protected void checkVectorDimensions(int n)
        throws DimensionMismatchException {
        if (data.length != n) {
            throw new DimensionMismatchException(data.length, n);
        }
    }

    
Check if any coordinate of this vector is NaN. 
Returns:
true if any coordinate of this vector is NaN, false otherwise./**
     * Check if any coordinate of this vector is {@code NaN}.
     *
     * @return {@code true} if any coordinate of this vector is {@code NaN},
     * {@code false} otherwise.
     */
    @Override
    public boolean isNaN() {
        for (double v : data) {
            if (Double.isNaN(v)) {
                return true;
            }
        }
        return false;
    }

    
Check whether any coordinate of this vector is infinite and none are NaN. 
Returns:
true if any coordinate of this vector is infinite and none are NaN, false otherwise./**
     * Check whether any coordinate of this vector is infinite and none
     * are {@code NaN}.
     *
     * @return {@code true} if any coordinate of this vector is infinite and
     * none are {@code NaN}, {@code false} otherwise.
     */
    @Override
    public boolean isInfinite() {
        if (isNaN()) {
            return false;
        }

        for (double v : data) {
            if (Double.isInfinite(v)) {
                return true;
            }
        }

        return false;
    }

    
{@inheritDoc} /** {@inheritDoc} */
    @Override
    public boolean equals(Object other) {
        if (this == other) {
            return true;
        }

        if (!(other instanceof RealVector)) {
            return false;
        }

        RealVector rhs = (RealVector) other;
        if (data.length != rhs.getDimension()) {
            return false;
        }

        if (rhs.isNaN()) {
            return this.isNaN();
        }

        for (int i = 0; i < data.length; ++i) {
            if (data[i] != rhs.getEntry(i)) {
                return false;
            }
        }
        return true;
    }

    
{@inheritDoc} All NaN values have the same hash code. /**
     * {@inheritDoc} All {@code NaN} values have the same hash code.
     */
    @Override
    public int hashCode() {
        if (isNaN()) {
            return 9;
        }
        return MathUtils.hash(data);
    }

    
{@inheritDoc} /** {@inheritDoc} */
    @Override
    public ArrayRealVector combine(double a, double b, RealVector y)
        throws DimensionMismatchException {
        return copy().combineToSelf(a, b, y);
    }

    
{@inheritDoc} /** {@inheritDoc} */
    @Override
    public ArrayRealVector combineToSelf(double a, double b, RealVector y)
        throws DimensionMismatchException {
        if (y instanceof ArrayRealVector) {
            final double[] yData = ((ArrayRealVector) y).data;
            checkVectorDimensions(yData.length);
            for (int i = 0; i < this.data.length; i++) {
                data[i] = a * data[i] + b * yData[i];
            }
        } else {
            checkVectorDimensions(y);
            for (int i = 0; i < this.data.length; i++) {
                data[i] = a * data[i] + b * y.getEntry(i);
            }
        }
        return this;
    }

    
{@inheritDoc} /** {@inheritDoc} */
    @Override
    public double walkInDefaultOrder(final RealVectorPreservingVisitor visitor) {
        visitor.start(data.length, 0, data.length - 1);
        for (int i = 0; i < data.length; i++) {
            visitor.visit(i, data[i]);
        }
        return visitor.end();
    }

    
{@inheritDoc} /** {@inheritDoc} */
    @Override
    public double walkInDefaultOrder(final RealVectorPreservingVisitor visitor,
        final int start, final int end) throws NumberIsTooSmallException,
        OutOfRangeException {
        checkIndices(start, end);
        visitor.start(data.length, start, end);
        for (int i = start; i <= end; i++) {
            visitor.visit(i, data[i]);
        }
        return visitor.end();
    }

    
{@inheritDoc}
In this implementation, the optimized order is the default order.
/**
     * {@inheritDoc}
     *
     * In this implementation, the optimized order is the default order.
     */
    @Override
    public double walkInOptimizedOrder(final RealVectorPreservingVisitor visitor) {
        return walkInDefaultOrder(visitor);
    }

    
{@inheritDoc}
In this implementation, the optimized order is the default order.
/**
     * {@inheritDoc}
     *
     * In this implementation, the optimized order is the default order.
     */
    @Override
    public double walkInOptimizedOrder(final RealVectorPreservingVisitor visitor,
        final int start, final int end) throws NumberIsTooSmallException,
        OutOfRangeException {
        return walkInDefaultOrder(visitor, start, end);
    }

    
{@inheritDoc} /** {@inheritDoc} */
    @Override
    public double walkInDefaultOrder(final RealVectorChangingVisitor visitor) {
        visitor.start(data.length, 0, data.length - 1);
        for (int i = 0; i < data.length; i++) {
            data[i] = visitor.visit(i, data[i]);
        }
        return visitor.end();
    }

    
{@inheritDoc} /** {@inheritDoc} */
    @Override
    public double walkInDefaultOrder(final RealVectorChangingVisitor visitor,
        final int start, final int end) throws NumberIsTooSmallException,
        OutOfRangeException {
        checkIndices(start, end);
        visitor.start(data.length, start, end);
        for (int i = start; i <= end; i++) {
            data[i] = visitor.visit(i, data[i]);
        }
        return visitor.end();
    }

    
{@inheritDoc}
In this implementation, the optimized order is the default order.
/**
     * {@inheritDoc}
     *
     * In this implementation, the optimized order is the default order.
     */
    @Override
    public double walkInOptimizedOrder(final RealVectorChangingVisitor visitor) {
        return walkInDefaultOrder(visitor);
    }

    
{@inheritDoc}
In this implementation, the optimized order is the default order.
/**
     * {@inheritDoc}
     *
     * In this implementation, the optimized order is the default order.
     */
    @Override
    public double walkInOptimizedOrder(final RealVectorChangingVisitor visitor,
        final int start, final int end) throws NumberIsTooSmallException,
        OutOfRangeException {
        return walkInDefaultOrder(visitor, start, end);
    }
}