mathutils.java

来自「是实现关系型贝叶斯网络一中机器学习算法」· Java 代码 · 共 109 行

package rmn;

import java.lang.reflect.*;

class MathUtils {

  static public void dotProduct(double[] v1, double v2[])
  {
    assert v1.length == v2.length : v2.length;

    for (int i = 0; i < v1.length; i++) {
      v1[i] = v1[i] * v2[i];
      assert !Double.isNaN(v1[i]) : v2[i];
      assert !Double.isInfinite(v1[i]) : v2[i];
    }
  }

  static public void dotQuotient(double[] v1, double v2[])
  {
    assert v1.length == v2.length : v2.length;

    for (int i = 0; i < v1.length; i++) {
      if (v2[i] == 0) {
	System.out.println("Quotient by zero!");
	System.exit(1);
      }
      assert !Double.isNaN(v1[i]) : v1[i];
      assert !Double.isNaN(v2[i]) : v2[i];
      v1[i] = v1[i] / v2[i];
      assert !Double.isNaN(v1[i]) : v2[i];
      assert !Double.isInfinite(v1[i]) : v2[i];
    }
  }

  static public double[] clone(double[] v)
  {
    double[] w = new double[v.length];
    System.arraycopy(v, 0, w, 0, v.length);

    return w;
  }

  static public void normalize(double[] v)
  {
    double total = 0;
    for (int i = 0; i < v.length; i++)
      total += v[i];

    if (Double.isNaN(total) || Double.isInfinite(total) || total == 0) {
      for (int i = 0; i < v.length; i++)
	System.out.println("v[" + i + "] = " + v[i]);
    }
    assert !Double.isNaN(total);
    assert !Double.isInfinite(total);
    assert total != 0;

    for (int i = 0; i < v.length; i++) {
      v[i] = v[i] / total;
      assert !Double.isNaN(v[i]);
      assert !Double.isInfinite(v[i]);
    }
  }

  static public boolean approxeq(double[] v1, double[] v2, double tol)
  {
    assert v1.length == v2.length : v2.length;
    for (int i = 0; i < v1.length; i++)
      if (Math.abs(v1[i] - v2[i]) > tol)
        return false;

    return true;
  }

  static public Method getSumOrMax(boolean bMaximize)
  {
    Method method = null;
    try {
      Class theClass = Class.forName("rmn.MathUtils");
      Class[] paramTypes = {Double.TYPE, Double.TYPE};
      method = theClass.getMethod("sum", paramTypes);
      if (bMaximize)
        method = theClass.getMethod("max", paramTypes);
    }
    catch (Exception e) {
      System.err.println(e);
      System.exit(1);
    }
      
    return method;
  }

  static public double sum(double a, double b)
  {
    double res = a + b;
    assert !Double.isNaN(res) : a;
    assert !Double.isInfinite(res) : a;
    return a + b;
  }

  static public double max(double a, double b)
  {
    if (a > b)
      return a;
    return b;
  }


}