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Fast double-precision vector and matrix maths library for Java, supporting N-dimensional numeric arrays.

There is a newer version: 0.67.0

package mikera.matrixx.impl;

import mikera.arrayz.ISparse;
import mikera.matrixx.AMatrix;
import mikera.vectorz.AVector;

/**
 * A matrix implemented as a quadtree of submatrices. 
 * 
 * Useful for large matrices with heirarchical structure where large regions are either fully sparse
 * or of a specialised subtype (e.g. a diagonal matrix).
 * 
 * @author Mike
 *
 */
public class QuadtreeMatrix extends ABlockMatrix implements ISparse {
	private static final long serialVersionUID = -7267626771473908891L;

	// Quadtree subcompoents
	private final AMatrix c00, c01, c10, c11;
	
	private final int rowSplit;
	private final int columnSplit;
	
	private QuadtreeMatrix(AMatrix c00, AMatrix c01, AMatrix c10, AMatrix c11) {
		super(c00.rowCount()+c10.rowCount(),c00.columnCount()+c01.columnCount());
		this.c00=c00;
		this.c01=c01;
		this.c10=c10;
		this.c11=c11;
		this.rowSplit= c00.rowCount();
		this.columnSplit=c00.columnCount();
	}
	
	public static QuadtreeMatrix wrap(AMatrix c00, AMatrix c01, AMatrix c10, AMatrix c11) {
		if (c00.rowCount()!=c01.rowCount()) throw new IllegalArgumentException("Mismtached submatrix size");
		if (c10.rowCount()!=c11.rowCount()) throw new IllegalArgumentException("Mismtached submatrix size");
		if (c00.columnCount()!=c10.columnCount()) throw new IllegalArgumentException("Mismtached submatrix size");
		if (c01.columnCount()!=c11.columnCount()) throw new IllegalArgumentException("Mismtached submatrix size");
		return new QuadtreeMatrix(c00,c01,c10,c11);
	}
	
	public static QuadtreeMatrix create(AMatrix c00, AMatrix c01, AMatrix c10, AMatrix c11) {
		return wrap(c00.copy(),c01.copy(),c10.copy(),c11.copy());
	}
	
	@Override
	public boolean isFullyMutable() {
		return c00.isFullyMutable()&&c01.isFullyMutable()&&c10.isFullyMutable()&&(c11.isFullyMutable());
	}
	
	@Override
	public boolean isMutable() {
		return (c00.isMutable())||(c01.isMutable())||(c10.isMutable())||(c11.isMutable());
	}
	
	@Override
	public boolean isZero() {
		return c00.isZero()&&c01.isZero()&&c10.isZero()&&(c11.isZero());
	}
	
	@Override
	public boolean isDiagonal() {
		if (!isSquare()) return false;
		if (columnSplit==rowSplit) {
			return (c01.isZero())&&(c10.isZero())&&(c00.isDiagonal())&&(c11.isDiagonal());
		} else {
			return super.isDiagonal();
		}
	}

	@Override
	public double get(int row, int column) {
		checkIndex(row,column);
		return unsafeGet(row,column);
	}

	@Override
	public void set(int row, int column, double value) {
		checkIndex(row,column);
		unsafeSet(row,column,value);
	}
	
	@Override
	public double unsafeGet(int row, int column) {
		if (row