/*
* Copyright 1998-2014 University Corporation for Atmospheric Research/Unidata
*
* Portions of this software were developed by the Unidata Program at the
* University Corporation for Atmospheric Research.
*
* Access and use of this software shall impose the following obligations
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* any fee or cost, to use, copy, modify, alter, enhance and distribute
* this software, and any derivative works thereof, and its supporting
* documentation for any purpose whatsoever, provided that this entire
* notice appears in all copies of the software, derivative works and
* supporting documentation. Further, UCAR requests that the user credit
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* software or in any product that includes this software. The names UCAR
* and/or Unidata, however, may not be used in any advertising or publicity
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*
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL UCAR/UNIDATA BE LIABLE FOR ANY SPECIAL,
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*/
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<nrows; i++) {
double sum = 0.0;
for (int k=0; k<ncols; k++)
sum += getDouble(i, k) * v.getDouble(k);
result.setDouble( imr.set(i), sum);
}
return new MAVector( result);
}
/**
* Matrix multiply: return m1 * m2.
* @param m1 left matrix
* @param m2 right matrix
* @return MAMatrix result: new matrix
* @exception IllegalArgumentException if m1.getNcols() != m2.getNrows().
*/
static public MAMatrix multiply(MAMatrix m1, MAMatrix m2) {
if (m1.getNcols() != m2.getNrows())
throw new IllegalArgumentException("MAMatrix.multiply "+m1.getNcols()+" != "+ m2.getNrows());
int kdims = m1.getNcols();
ArrayDouble.D2 result = new ArrayDouble.D2(m1.getNrows(), m2.getNcols());
Index imr = result.getIndex();
for (int i=0; i<m1.getNrows(); i++) {
for (int j=0; j<m2.getNcols(); j++) {
double sum = 0.0;
for (int k=0; k<kdims; k++)
sum += m1.getDouble(i, k) * m2.getDouble(k, j);
result.setDouble( imr.set(i,j), sum);
}
}
return new MAMatrix( result);
}
/**
* Matrix multiply by a diagonal matrix, store result in this: this = this * diag
* @param diag diagonal matrix stored as a Vector
* @exception IllegalArgumentException if ncols != diag.getNelems().
*/
public void postMultiplyDiagonal(MAVector diag) {
if (ncols != diag.getNelems())
throw new IllegalArgumentException("MAMatrix.postMultiplyDiagonal "+ncols+" != "+ diag.getNelems());
for (int i=0; i<nrows; i++) {
for (int j=0; j<ncols; j++) {
double val = a.getDouble( ima.set(i,j)) * diag.getDouble(j);
a.setDouble( ima, val);
}
}
}
/**
* Matrix multiply by a diagonal matrix, store result in this: this = diag * this
* @param diag diagonal matrix stored as a Vector
* @exception IllegalArgumentException if nrows != diag.getNelems().
*/
public void preMultiplyDiagonal(MAVector diag) {
if (nrows != diag.getNelems())
throw new IllegalArgumentException("MAMatrix.preMultiplyDiagonal "+nrows+" != "+ diag.getNelems());
for (int i=0; i<nrows; i++) {
for (int j=0; j<ncols; j++) {
double val = a.getDouble( ima.set(i,j)) * diag.getDouble(i);
a.setDouble( ima, val);
}
}
}
}