ucar.ma2.MAMatrix Maven / Gradle / Ivy
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/*
* Copyright (c) 1998-2018 University Corporation for Atmospheric Research/Unidata
* See LICENSE for license information.
*/
package ucar.ma2;
/**
* Abstraction for matrix operations.
* A matrix is a rank-2 Array: m[rows, cols].
* All operations done in double precision
*
* @author @caron
*/
public class MAMatrix {
private Array a;
private int nrows, ncols;
private Index ima;
/**
* Create an MAMatrix of the given shape.
* @param nrows number of rows
* @param ncols number of cols
*/
public MAMatrix( int nrows, int ncols) {
this.a = new ArrayDouble.D2(nrows, ncols);
this.nrows = nrows;
this.ncols = ncols;
ima = a.getIndex();
}
/**
* Create an MAMatrix using the given rank-2 array.
* @param a rank-2 array
* @exception IllegalArgumentException is a is not rank 2
*/
public MAMatrix( Array a) {
this.a = a;
if (a.getRank() != 2)
throw new IllegalArgumentException("rank != 2, instead = "+ a.getRank());
nrows = a.getShape()[0];
ncols = a.getShape()[1];
ima = a.getIndex();
}
public int getNrows() { return nrows; }
public int getNcols() { return ncols; }
public double getDouble(int i, int j) { return a.getDouble(ima.set(i,j)); }
public void setDouble(int i, int j, double val) { a.setDouble(ima.set(i,j), val); }
/**
* Create a new MAMatrix that is the same as this one, with a copy of the backing store.
*/
public MAMatrix copy() {
return new MAMatrix( a.copy());
}
/**
* Create a MAMatrix that is the transpose of this one, with the same backing store.
* Use copy() to get a copy.
*/
public MAMatrix transpose() {
return new MAMatrix( a.transpose(0,1));
}
/**
* Get the jth column, return as a MAVector: same backing store.
*/
public MAVector column(int j) {
return new MAVector( a.slice(1,j));
}
/**
* Get the ith row, return as a MAVector: same backing store.
*/
public MAVector row(int i) {
return new MAVector( a.slice(0,i));
}
/**
* Dot product of matrix and vector: return M dot v
* @param v dot product with this vector
* @return MAVector result: new vector
* @exception IllegalArgumentException if ncols != v.getSize().
*/
public MAVector dot(MAVector v) {
if (ncols != v.getNelems())
throw new IllegalArgumentException("MAMatrix.dot "+ncols+" != "+ v.getNelems());
ArrayDouble.D1 result = new ArrayDouble.D1(nrows);
Index imr = result.getIndex();
for (int i=0; i