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 String getReadableSize(long bytes, boolean si) {
    int unit = si ? 1000 : 1024;
    if (bytes < unit)
        return bytes + " B";
    int exp = (int) (Math.log(bytes) / Math.log(unit));
    String pre = (si ? "kMGTPE" : "KMGTPE").charAt(exp - 1) + (si ? "" : "i");
    return String.format("%.1f %sB", bytes / Math.pow(unit, exp), pre);
}

From source file:Main.java

public static String humanReadableCount(long bytes, boolean si) {
    int unit = si ? 1000 : 1024;
    if (bytes < unit)
        return bytes + " B";
    int exp = (int) (Math.log(bytes) / Math.log(unit));
    char pre = "KMGTPE".charAt(exp - 1);
    return String.format("%.2f %s" + (si ? "bps" : "B"), bytes / Math.pow(unit, exp), pre);
}

From source file:Main.java

public static double logSumExp(double a, double b) {
    double x = (a < b) ? a : b;
    double y = (a < b) ? b : a;
    if (y - x > 50) {
        return y;
    } else {//from  w w w  . ja va  2  s.  c om
        return x + Math.log(1.0 + Math.exp(y - x));
    }
}

From source file:Main.java

@SuppressLint("DefaultLocale")
public static String formatByteString(long bytes, boolean si) {
    int unit = si ? 1000 : 1024;
    if (bytes < unit)
        return bytes + " B";
    int exp = (int) (Math.log(bytes) / Math.log(unit));
    String pre = (si ? "kMGTPE" : "KMGTPE").charAt(exp - 1) + (si ? "" : "i");
    return String.format("%.1f %sB", bytes / Math.pow(unit, exp), pre);
}

From source file:Main.java

public static int latitudeToPixelY(double latitude, double zoomLevel, int tileSize) {
    double sinLatitude = Math.sin(latitude * (Math.PI / 180));
    int mapSize = getMapSize(zoomLevel, tileSize);
    return (int) Math
            .round((0.5d - Math.log((1d + sinLatitude) / (1d - sinLatitude)) / (4d * Math.PI)) * mapSize);
}

From source file:Main.java

public static String getHumanReadableByteCount(final long bytes, final boolean si) {
    final int unit = si ? 1000 : 1024;
    if (bytes < unit) {
        return bytes + " B";
    } else {/*from  w  ww . j  a  v a  2  s. c om*/
        final int exp = (int) (Math.log(bytes) / Math.log(unit));
        final String pre = (si ? "kMGTPE" : "KMGTPE").charAt(exp - 1) + (si ? "" : "i");
        return String.format("%.1f %sB", bytes / Math.pow(unit, exp), pre);
    }
}

From source file:Main.java

public static int scalePow2(int height, int width) {
    int scale = 1;
    int size = Math.max(height, width);
    if (size > IMAGE_MAX_SIZE) {
        scale = (int) Math.pow(2, (int) Math.round(Math.log(IMAGE_MAX_SIZE / (double) size) / Math.log(0.5)));
    }/*from  www  .java 2s .  c o m*/
    return scale;
}

From source file:Main.java

public static double[] complexMagnitude(double[] complexInput) {
    double[] magnitude = new double[complexInput.length / 2];
    for (int i = 0; i < complexInput.length / 2; i++) {
        double re = complexInput[2 * i];
        double im = complexInput[2 * i + 1];
        magnitude[i] = Math.log(re * re + im * im + 0.001);
    }/*  ww  w.  j  a  v  a  2  s .com*/
    return magnitude;
}

From source file:Main.java

public static int[] getMapTileFromCoordinates(final double aLat, final double aLon, final int zoom) {
    final int[] out = new int[2];

    final double E2 = (double) aLat * Math.PI / 180;
    final long sradiusa = 6378137;
    final long sradiusb = 6356752;
    final double J2 = (double) Math.sqrt(sradiusa * sradiusa - sradiusb * sradiusb) / sradiusa;
    final double M2 = (double) Math.log((1 + Math.sin(E2)) / (1 - Math.sin(E2))) / 2
            - J2 * Math.log((1 + J2 * Math.sin(E2)) / (1 - J2 * Math.sin(E2))) / 2;
    final double B2 = (double) (1 << zoom);
    out[0] = (int) Math.floor(B2 / 2 - M2 * B2 / 2 / Math.PI);

    out[1] = (int) Math.floor((aLon + 180) / 360 * (1 << zoom));

    return out;//w w w  .  j  a  v a  2 s . co m
}

From source file:Main.java

public static double[] geoToMercator(double[] g) {
    double d = g[0] * Math.PI / 180, m = g[1] * Math.PI / 180, l = 6378137, k = 0.0818191908426,
            f = k * Math.sin(m);/* w  w  w  .  j  a v  a2s .c o  m*/
    double h = Math.tan(Math.PI / 4 + m / 2), j = Math.pow(Math.tan(Math.PI / 4 + Math.asin(f) / 2), k),
            i = h / j;
    // return new DoublePoint(Math.round(l * d), Math.round(l *
    // Math.log(i)));
    return new double[] { l * d, l * Math.log(i) };
}