Util.java

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package jarmos;

import java.util.Arrays;
import java.util.Random;

import org.apache.commons.math.linear.RealMatrix;
import org.apache.commons.math.linear.RealVector;

public class Util {
    public static double[] linspace(double a, double b, int num) {
        double[] res = new double[num];
        double step = (b - a) / (num - 2);
        for (int i = 0; i < num - 1; i++) {
            res[i] = a + i * step;
        }
        res[num - 1] = b;
        return res;
    }

    public static double[] range(double a, double step, double b) {
        // int num = (int) Math.ceil((b - a) / step);
        if (a > b)
            return null;
        int num = 1;
        double hlp = a + step;
        while (hlp <= b) {
            hlp += step;
            num++;
        }
        double[] res = new double[num];
        for (int i = 0; i < num; i++) {
            res[i] = a + i * step;
        }
        return res;
    }

    public static void vecAdd(double[] to, double[] what) {
        for (int i = 0; i < to.length; i++) {
            to[i] += what[i];
        }
    }

    public static RealVector randVector(int dim) {
        Random r = new Random();
        r.setSeed(System.currentTimeMillis());
        RealVector res = MathFactory.createRealVector(dim);
        for (int i = 0; i < dim; i++) {
            res.setEntry(i, r.nextDouble());
        }
        return res;
    }

    public static RealMatrix randMatrix(int rows, int cols) {
        RealMatrix res = MathFactory.createRealMatrix(rows, cols);
        for (int i = 0; i < rows; i++) {
            res.setRow(i, randVector(cols).getData());
        }
        return res;
    }

    public static String realMatToString(RealMatrix r) {
        String res = "RealMatrix(" + r.getRowDimension() + "x" + r.getColumnDimension() + ") of type '"
                + r.getClass().getName() + "'\n";
        for (int i = 0; i < r.getRowDimension(); i++) {
            res += Arrays.toString(r.getRow(i)) + "\n";
        }
        return res;
    }

    public static String realVecToString(RealVector r) {
        String res = "RealVector(" + r.getDimension() + ") of type '" + r.getClass().getName() + "'\n";
        return res += Arrays.toString(r.getData()) + "\n";
    }

}