Example usage for java.lang Math log

Introduction

In this page you can find the example usage for java.lang Math log.

Prototype

@HotSpotIntrinsicCandidate
public static double log(double a)

Source Link

Document

Returns the natural logarithm (base e) of a double value.

Usage

From source file:Main.java

public static double polarFunction(double t, double A, double B, double N) {
    return A / Math.log(B * Math.tan(t / (2 * N)));
}

From source file:com.idylwood.Statistics.java

private static double[][] data(List<YahooFinance.Pair> pairs) {
    double[][] data = new double[pairs.size() - 1][2];
    for (int i = 0; i < pairs.size() - 1; i++) {
        data[i][0] = Math.log(pairs.get(i + 1).first / pairs.get(i).first);
        data[i][1] = Math.log(pairs.get(i + 1).second / pairs.get(i).second);
    }/*w ww.j  a  v a  2  s . c o m*/
    return data;
}

From source file:Main.java

public static double gamma(double x) {
    double g = 1.0;
    double f;//from w  w w .ja  v  a2  s .c o  m
    if (x > 0.0) {
        while (x < 3.0) {
            g *= x;
            ++x;
        }
        f = (1.0 - 2.0 / (7.0 * Math.pow(x, 2.0)) * (1.0 - 2.0 / (3.0 * Math.pow(x, 2.0))))
                / (30.0 * Math.pow(x, 2.0));
        f = (1.0 - f) / (12.0 * x) + x * (Math.log(x) - 1.0);
        f = Math.exp(f) / g * Math.pow(6.283185307179586 / x, 0.5);
    } else {
        f = Double.POSITIVE_INFINITY;
    }
    return f;
}

From source file:conceptor.chaos.Lyapunov.java

/**
   Given a DynamicalSystem, returns the maximul lyapunov exponent
   using the method outline by J.C. Sprott see:
   http://sprott.physics.wisc.edu/chaos/lyapexp.htm
 *//*  ww  w  . j av a 2s  .  com*/
public static double computeLargestExponent(DynamicalSystem system) {

    double d0 = 10e-8;

    // First, evolve the system such that it's very likely to be on
    // the attractor (1000 iterations is a decent guess)
    evolveSystem(system, 10000);

    // Next, pick a test point a distance d0 away
    double[] testPoint = getTestPoint(system, d0);
    double[] x = system.getState();

    double d1 = 0.0;
    double l = 0.0;

    // Evolve both the test point and the original
    for (int i = 0; i < 64100; i++) {

        testPoint = system.evolveOther(testPoint);
        x = system.evolve();

        // Test for unbounded orbits
        if (isUnbounded(x)) {
            return Double.NaN;
        }

        // Compute distance
        d1 = MathArrays.distance(testPoint, x);

        // Compute lyapunov exponent this round
        if (i > 100) {
            l = l + Math.log(d1 / d0);
        }

        // Renormalize test point
        for (int j = 0; j < x.length; j++) {
            testPoint[j] = x[j] + (d0 / d1) * (testPoint[j] - x[j]);
        }
    }
    return l / (63999 * system.getStepSize());
}

From source file:edu.asu.ca.kaushik.algorithms.permvector.utils.SCPHF.java

public static int SCPHF_LLL(int t, int k, int v) {
    double covP = 1.0d;

    for (int i = 1; i < t; i++) {
        covP = covP * (1.0d - 1 / Math.pow(v, i));
    }//from  w w w .j  a  va  2s.c  o m

    double q = 1.0d - covP;

    double d = CombinatoricsUtils.binomialCoefficientDouble(k, t)
            - CombinatoricsUtils.binomialCoefficientDouble(k - t, t);

    return (int) Math.ceil((1 + Math.log(d)) / (-Math.log(q)));
}

From source file:com.opengamma.analytics.financial.model.volatility.surface.LogMoneyness.java

public LogMoneyness(final double strike, final double forward) {
    Validate.isTrue(strike > 0, "negative or zero strike");
    Validate.isTrue(forward > 0, "negative or zero forward");
    _value = Math.log(strike / forward);
}

From source file:com.wegas.core.jcr.content.ContentConnector.java

/**
 * @param bytes/*from w  w w . java2s.c  o m*/
 * @return string representation
 */
public static String bytesToHumanReadable(Long bytes) {
    Integer unit = 1024;
    if (bytes < unit) {
        return bytes + "B";
    }
    Integer exponent = (int) (Math.log(bytes) / Math.log(unit));
    String prefix = ("KMGTPE").charAt(exponent - 1) + "";
    return String.format("%.1f%sB", bytes / Math.pow(unit, exponent), prefix);
}

From source file:Util.java

/**
 * Returns the KL divergence, K(p1 || p2).
 *
 * The log is w.r.t. base 2. <p>/*from ww w.j  av a 2 s .  c om*/
 *
 * *Note*: If any value in <tt>p2</tt> is <tt>0.0</tt> then the KL-divergence
 * is <tt>infinite</tt>. Limin changes it to zero instead of infinite. 
 * 
 */
public static double klDivergence(double[] p1, double[] p2) {

    double klDiv = 0.0;

    for (int i = 0; i < p1.length; ++i) {
        if (p1[i] == 0) {
            continue;
        }
        if (p2[i] == 0.0) {
            continue;
        } // Limin

        klDiv += p1[i] * Math.log(p1[i] / p2[i]);
    }

    return klDiv / log2; // moved this division out of the loop -DM
}

From source file:gedi.util.math.stat.distributions.LfcDistribution.java

public static double mean(double a, double b) {
    return (Gamma.digamma(a) - Gamma.digamma(b)) / Math.log(2);
}

From source file:com.opengamma.analytics.financial.timeseries.returns.ContinuouslyCompoundedGeometricMeanReturnCalculator.java

@Override
public Double evaluate(final double[] x) {
    Validate.notNull(x, "x");
    ArgumentChecker.notEmpty(x, "x");
    final int n = x.length;
    double mult = Math.exp(x[0]);
    for (int i = 1; i < n; i++) {
        mult *= Math.exp(x[i]);/* w w  w .j a  v  a  2s  .com*/
    }
    return Math.log(mult) / n;
}