JSci.maths.vectors.DoubleSparseVector Maven / Gradle / Ivy
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JSci is a set of open source Java packages. The aim is to encapsulate scientific methods/principles in the most natural way possible. As such they should greatly aid the development of scientific based software.
It offers: abstract math interfaces, linear algebra (support for various matrix and vector types), statistics (including probability distributions), wavelets, newtonian mechanics, chart/graph components (AWT and Swing), MathML DOM implementation, ...
Note: some packages, like javax.comm, for the astro and instruments package aren't listed as dependencies (not available).
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package JSci.maths.vectors;
import JSci.GlobalSettings;
import JSci.maths.MathDouble;
import JSci.maths.MathInteger;
import JSci.maths.Mapping;
import JSci.maths.matrices.DoubleSparseMatrix;
import JSci.maths.groups.AbelianGroup;
import JSci.maths.algebras.Module;
import JSci.maths.algebras.VectorSpace;
import JSci.maths.fields.Ring;
import JSci.maths.fields.Field;
/**
* The DoubleSparseVector class encapsulates sparse vectors.
* Uses Morse-coding.
* @author Daniel Lemire
* @author Alain Beliveau
*/
public final class DoubleSparseVector extends AbstractDoubleVector {
private double vector[];
/**
* Sparse indexing data.
* Contains the component positions of each element,
* e.g. pos[n] is the component position
* of the nth element
* (the pos[n]th component is stored at index n).
*/
private int pos[];
private int count = 0;
/**
* Amount by which to increase the capacity.
*/
private int capacityIncrement = 1;
/**
* Constructs an empty vector.
* @param dim the dimension of the vector.
*/
public DoubleSparseVector(final int dim) {
super(dim);
vector=new double[0];
pos=new int[0];
}
public DoubleSparseVector(final int dim, int capacityIncrement) {
this(dim);
this.capacityIncrement = capacityIncrement;
}
/**
* Constructs a vector from an array.
*/
public DoubleSparseVector(double array[]) {
super(array.length);
int n=0;
for(int i=0;iGlobalSettings.ZERO_TOL)
n++;
}
count = n;
vector=new double[n];
pos=new int[n];
n=0;
for(int i=0;iGlobalSettings.ZERO_TOL) {
vector[n]=array[i];
pos[n]=i;
n++;
}
}
}
/**
* Compares two vectors for equality.
* @param obj a double sparse vector
*/
public boolean equals(Object obj, double tol) {
if(obj!=null && (obj instanceof DoubleSparseVector) && N==((DoubleSparseVector)obj).N) {
DoubleSparseVector v=(DoubleSparseVector)obj;
double sumSqr = 0.0;
for(int i=0; i=N)
throw new VectorDimensionException(getInvalidComponentMsg(n));
int k = 0;
while(k=N)
throw new VectorDimensionException(getInvalidComponentMsg(n));
int k = 0;
while(k GlobalSettings.ZERO_TOL) {
// expand
if(count == vector.length) {
// increase capacity
double oldVector[] = vector;
int oldPos[] = pos;
vector=new double[oldVector.length+capacityIncrement];
pos=new int[oldPos.length+capacityIncrement];
System.arraycopy(oldVector,0,vector,0,k);
System.arraycopy(oldPos,0,pos,0,k);
System.arraycopy(oldVector,k,vector,k+1,oldVector.length-k);
System.arraycopy(oldPos,k,pos,k+1,oldPos.length-k);
} else {
System.arraycopy(vector,k,vector,k+1,count-k);
System.arraycopy(pos,k,pos,k+1,count-k);
}
vector[k] = x;
pos[k] = n;
count++;
}
}
/**
* Returns the number of non-zero components.
*/
public int componentCount() {
return count;
}
/**
* Returns the l2-norm (magnitude).
*/
public double norm() {
return Math.sqrt(sumSquares());
}
/**
* Returns the sum of the squares of the components.
*/
public double sumSquares() {
double norm=0.0;
for(int k=0;k