/*
* 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
* and understandings on the user. The user is granted the right, without
* 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
* UCAR/Unidata in any publications that result from the use of this
* 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
* to endorse or promote any products or commercial entity unless specific
* written permission is obtained from UCAR/Unidata. The user also
* understands that UCAR/Unidata is not obligated to provide the user with
* any support, consulting, training or assistance of any kind with regard
* to the use, operation and performance of this software nor to provide
* the user with any updates, revisions, new versions or "bug fixes."
*
* THIS SOFTWARE IS PROVIDED BY UCAR/UNIDATA "AS IS" AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL UCAR/UNIDATA BE LIABLE FOR ANY SPECIAL,
* INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING
* FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
* NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
* WITH THE ACCESS, USE OR PERFORMANCE OF THIS SOFTWARE.
*/
package ucar.ma2;
/**
* Abstraction for vector operations.
* A vector is a rank-1 Array.
* All operations done in double precision
*
* @author @caron
*/
public class MAVector {
private Array a;
private int nelems;
private Index ima;
/**
* Create an MAVector out of a double array
*/
public MAVector( double[] values) {
this( Array.factory( values));
}
/**
* Create an MAVector of the given length.
*/
public MAVector( int nelems) {
this.a = new ArrayDouble.D1(nelems);
this.nelems = nelems;
ima = a.getIndex();
}
/**
* Create an MAVector using the given rank-1 array.
* @param a rank-1 array
* @exception IllegalArgumentException is a is not rank 1
*/
public MAVector( Array a) {
this.a = a;
if (a.getRank() != 1)
throw new IllegalArgumentException("rank != 1, instead = "+ a.getRank());
nelems = a.getShape()[0];
ima = a.getIndex();
}
public int getNelems() { return nelems; }
public double getDouble(int i) { return a.getDouble(ima.set(i)); }
public void setDouble(int i, double val) { a.setDouble(ima.set(i), val); }
/**
* Create a new MAVector that is the same as this one, with a copy of the backing store.
*/
public MAVector copy() {
return new MAVector( a.copy());
}
/**
* Cos between two vectors = dot(v) / norm() * norm(v)
* @param v cosine with this vector
* @return double result: cos between this and v
* @exception IllegalArgumentException if nelems != v.getNelems().
*/
public double cos(MAVector v) {
if (nelems != v.getNelems())
throw new IllegalArgumentException("MAVector.cos "+nelems+" != "+ v.getNelems());
double norm = norm();
double normV = v.norm();
if ((norm == 0.0) || (normV == 0.0))
return 0.0;
else
return dot(v)/(norm*normV);
}
/**
* Dot product of 2 vectors
* @param v dot product with this vector
* @return double result: dot product
* @exception IllegalArgumentException if nelems != v.getNelems().
*/
public double dot(MAVector v) {
if (nelems != v.getNelems())
throw new IllegalArgumentException("MAVector.dot "+nelems+" != "+ v.getNelems());
double sum = 0.0;
for (int k=0; k<nelems; k++)
sum += getDouble(k) * v.getDouble(k);
return sum;
}
/**
* Get the L2 norm of this vector.
* @return double norm
*/
public double norm() {
double sum = 0.0;
for (int k=0; k<nelems; k++) {
double val = getDouble(k);
sum += val * val;
}
return Math.sqrt(sum);
}
/**
* Normalize this vector, so it has norm = 1.0.
*/
public void normalize() {
double norm = norm();
if (norm <= 0.0)
return;
for (int k=0; k<nelems; k++) {
double val = getDouble(k);
setDouble(k, val/norm);
}
}
}