package mikera.matrixx.impl;

import java.util.Arrays;

import mikera.arrayz.impl.IDense;
import mikera.matrixx.AMatrix;
import mikera.matrixx.Matrix;
import mikera.vectorz.AVector;
import mikera.vectorz.Op;
import mikera.vectorz.impl.ArraySubVector;
import mikera.vectorz.util.DoubleArrays;

/**
 * A densely packed matrix organised in column-major format.
 * 
 * Transposes to/from a regular dense Matrix
 * 
 * This class is useful if your main performance requirement is fast access to columns of a matrix. 
 * This is frequently true when the matrix is used as the *second* argument in matrix/matrix operations.
 * 
 * @author Mike
 *
 */
public final class DenseColumnMatrix extends AStridedMatrix implements IFastColumns, IDense {
	private static final long serialVersionUID = 5459617932072332096L;

	private DenseColumnMatrix(int rowCount, int columnCount, double[] data) {
		super(data, rowCount, columnCount);
	}
	
	private DenseColumnMatrix(int rowCount, int columnCount) {
		this(rowCount, columnCount, DoubleArrays.createStorage(rowCount, columnCount));
	}
	
	public static DenseColumnMatrix wrap(int rows, int cols, double[] data) {
		return new DenseColumnMatrix(rows, cols, data);
	}
	
	public static DenseColumnMatrix create(AMatrix m) {
		DenseColumnMatrix dm= new DenseColumnMatrix(m.rowCount(), m.columnCount());
		dm.set(m);
		return dm;
	}
	
	@Override
	public int getArrayOffset() {
		return 0;
	}

	@Override
	public int rowStride() {
		return 1;
	}

	@Override
	public int columnStride() {
		return rows;
	}
	
	@Override
	public ArraySubVector getColumn(int j) {
		return ArraySubVector.wrap(data, j*rows, rows);
	}

	@Override
	public void copyRowTo(int i, double[] dest, int destOffset) {
		for (int j=0; j