class DoubleVector implements java.io.Serializable {

    public int numNonZeroEntries() {
        int count = 0;
        for (double element : this.doubleArray) {
            if (Double.compare(element, 0.0) != 0) {
                count++;
            }
        }
        return count;
    }

    public  DoubleVector();
    public  DoubleVector(double[] toCopy);
    public  DoubleVector(DoubleVector toCopy);

}