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:ExponentialDemo.java

public static void main(String[] args) {
    double x = 11.635;
    double y = 2.76;

    System.out.println("The value of e is " + Math.E);
    System.out.println("exp(" + x + ") is " + Math.exp(x));
    System.out.println("log(" + x + ") is " + Math.log(x));
    System.out.println("pow(" + x + ", " + y + ") is " + Math.pow(x, y));
    System.out.println("sqrt(" + x + ") is " + Math.sqrt(x));
}

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From source file:com.linkedin.pinot.perf.MultiValueReaderWriterBenchmark.java

public static void main(String[] args) throws Exception {
    List<String> lines = IOUtils.readLines(new FileReader(new File(args[0])));
    int totalDocs = lines.size();
    int max = Integer.MIN_VALUE;
    int maxNumberOfMultiValues = Integer.MIN_VALUE;
    int totalNumValues = 0;
    int data[][] = new int[totalDocs][];
    for (int i = 0; i < lines.size(); i++) {
        String line = lines.get(i);
        String[] split = line.split(",");
        totalNumValues = totalNumValues + split.length;
        if (split.length > maxNumberOfMultiValues) {
            maxNumberOfMultiValues = split.length;
        }/* www .  java 2  s  .  c  o m*/
        data[i] = new int[split.length];
        for (int j = 0; j < split.length; j++) {
            String token = split[j];
            int val = Integer.parseInt(token);
            data[i][j] = val;
            if (val > max) {
                max = val;
            }
        }
    }
    int maxBitsNeeded = (int) Math.ceil(Math.log(max) / Math.log(2));
    int size = 2048;
    int[] offsets = new int[size];
    int bitMapSize = 0;
    File outputFile = new File("output.mv.fwd");

    FixedBitSkipListSCMVWriter fixedBitSkipListSCMVWriter = new FixedBitSkipListSCMVWriter(outputFile,
            totalDocs, totalNumValues, maxBitsNeeded);

    for (int i = 0; i < totalDocs; i++) {
        fixedBitSkipListSCMVWriter.setIntArray(i, data[i]);
        if (i % size == size - 1) {
            MutableRoaringBitmap rr1 = MutableRoaringBitmap.bitmapOf(offsets);
            ByteArrayOutputStream bos = new ByteArrayOutputStream();
            DataOutputStream dos = new DataOutputStream(bos);
            rr1.serialize(dos);
            dos.close();
            //System.out.println("Chunk " + i / size + " bitmap size:" + bos.size());
            bitMapSize += bos.size();
        } else if (i == totalDocs - 1) {
            MutableRoaringBitmap rr1 = MutableRoaringBitmap.bitmapOf(Arrays.copyOf(offsets, i % size));
            ByteArrayOutputStream bos = new ByteArrayOutputStream();
            DataOutputStream dos = new DataOutputStream(bos);
            rr1.serialize(dos);
            dos.close();
            //System.out.println("Chunk " + i / size + " bitmap size:" + bos.size());
            bitMapSize += bos.size();
        }
    }
    fixedBitSkipListSCMVWriter.close();
    System.out.println("Output file size:" + outputFile.length());
    System.out.println("totalNumberOfDoc\t\t\t:" + totalDocs);
    System.out.println("totalNumberOfValues\t\t\t:" + totalNumValues);
    System.out.println("chunk size\t\t\t\t:" + size);
    System.out.println("Num chunks\t\t\t\t:" + totalDocs / size);
    int numChunks = totalDocs / size + 1;
    int totalBits = (totalNumValues * maxBitsNeeded);
    int dataSizeinBytes = (totalBits + 7) / 8;

    System.out.println("Raw data size with fixed bit encoding\t:" + dataSizeinBytes);
    System.out.println("\nPer encoding size");
    System.out.println();
    System.out.println("size (offset + length)\t\t\t:" + ((totalDocs * (4 + 4)) + dataSizeinBytes));
    System.out.println();
    System.out.println("size (offset only)\t\t\t:" + ((totalDocs * (4)) + dataSizeinBytes));
    System.out.println();
    System.out.println("bitMapSize\t\t\t\t:" + bitMapSize);
    System.out.println("size (with bitmap)\t\t\t:" + (bitMapSize + (numChunks * 4) + dataSizeinBytes));

    System.out.println();
    System.out.println("Custom Bitset\t\t\t\t:" + (totalNumValues + 7) / 8);
    System.out.println("size (with custom bitset)\t\t\t:"
            + (((totalNumValues + 7) / 8) + (numChunks * 4) + dataSizeinBytes));

}

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From source file:com.mapr.PurchaseLog.java

public static void main(String[] args) throws IOException {
    Options opts = new Options();
    CmdLineParser parser = new CmdLineParser(opts);
    try {//from www.  j a va 2s .c  o m
        parser.parseArgument(args);
    } catch (CmdLineException e) {
        System.err.println("Usage: -count <number>G|M|K [ -users number ]  log-file user-profiles");
        return;
    }

    Joiner withTab = Joiner.on("\t");

    // first generate lots of user definitions
    SchemaSampler users = new SchemaSampler(
            Resources.asCharSource(Resources.getResource("user-schema.txt"), Charsets.UTF_8).read());
    File userFile = File.createTempFile("user", "tsv");
    BufferedWriter out = Files.newBufferedWriter(userFile.toPath(), Charsets.UTF_8);
    for (int i = 0; i < opts.users; i++) {
        out.write(withTab.join(users.sample()));
        out.newLine();
    }
    out.close();

    // now generate a session for each user
    Splitter onTabs = Splitter.on("\t");
    Splitter onComma = Splitter.on(",");

    Random gen = new Random();
    SchemaSampler intermediate = new SchemaSampler(
            Resources.asCharSource(Resources.getResource("hit_step.txt"), Charsets.UTF_8).read());

    final int COUNTRY = users.getFieldNames().indexOf("country");
    final int CAMPAIGN = intermediate.getFieldNames().indexOf("campaign_list");
    final int SEARCH_TERMS = intermediate.getFieldNames().indexOf("search_keywords");
    Preconditions.checkState(COUNTRY >= 0, "Need country field in user schema");
    Preconditions.checkState(CAMPAIGN >= 0, "Need campaign_list field in step schema");
    Preconditions.checkState(SEARCH_TERMS >= 0, "Need search_keywords field in step schema");

    out = Files.newBufferedWriter(new File(opts.out).toPath(), Charsets.UTF_8);

    for (String line : Files.readAllLines(userFile.toPath(), Charsets.UTF_8)) {
        long t = (long) (TimeUnit.MILLISECONDS.convert(30, TimeUnit.DAYS) * gen.nextDouble());
        List<String> user = Lists.newArrayList(onTabs.split(line));

        // pick session length
        int n = (int) Math.floor(-30 * Math.log(gen.nextDouble()));

        for (int i = 0; i < n; i++) {
            // time on page
            int dt = (int) Math.floor(-20000 * Math.log(gen.nextDouble()));
            t += dt;

            // hit specific values
            JsonNode step = intermediate.sample();

            // check for purchase
            double p = 0.01;
            List<String> campaigns = Lists.newArrayList(onComma.split(step.get("campaign_list").asText()));
            List<String> keywords = Lists.newArrayList(onComma.split(step.get("search_keywords").asText()));
            if ((user.get(COUNTRY).equals("us") && campaigns.contains("5"))
                    || (user.get(COUNTRY).equals("jp") && campaigns.contains("7")) || keywords.contains("homer")
                    || keywords.contains("simpson")) {
                p = 0.5;
            }

            String events = gen.nextDouble() < p ? "1" : "-";

            out.write(Long.toString(t));
            out.write("\t");
            out.write(line);
            out.write("\t");
            out.write(withTab.join(step));
            out.write("\t");
            out.write(events);
            out.write("\n");
        }
    }
    out.close();
}

---

From source file:ml.shifu.shifu.udf.stats.CategoricalVarStats.java

public static void main(String[] args) {
    System.out.println(Math.log((9 * 1.0d / 21d) / (41 * 1.0d / 90d)));
}

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From source file:eu.crisis_economics.abm.model.configuration.LogNormalDistributionModelParameterConfiguration.java

/**
  * A lightweight test for this {@link ConfigurationComponent}. This snippet
  * creates a {@link Parameter}{@code <Double>} using an instance of
  * {@link LogNormalDistributionModelParameterConfiguration} and then tests
  * whether the logarithm of {@link Double} values drawn from this {@link Parameter}
  * have the expected mean.//from   ww  w .  jav a2  s.c o  m
  */
public static void main(String[] args) {
    {
        final LogNormalDistributionModelParameterConfiguration configuration = new LogNormalDistributionModelParameterConfiguration();
        configuration.setMu(5.0);
        configuration.setSigma(0.1);
        final ModelParameter<Double> distribution = configuration.createInjector()
                .getInstance(Key.get(new TypeLiteral<ModelParameter<Double>>() {
                }));
        double mean = 0.;
        final int numSamples = 10000000;
        for (int i = 0; i < numSamples; ++i) {
            final double value = Math.log(distribution.get());
            mean += value;
        }
        mean /= numSamples;
        Assert.assertTrue(Math.abs(mean - 5.) < 1.e-3);
    }
    {
        final LogNormalDistributionModelParameterConfiguration configuration = LogNormalDistributionModelParameterConfiguration
                .create(5., .1);
        final ModelParameter<Double> distribution = configuration.createInjector()
                .getInstance(Key.get(new TypeLiteral<ModelParameter<Double>>() {
                }));
        final Variance variance = new Variance();
        double mean = 0.;
        final int numSamples = 10000000;
        for (int i = 0; i < numSamples; ++i) {
            final double value = distribution.get();
            mean += value;
            variance.increment(value);
        }
        mean /= numSamples;
        final double observedSigma = Math.sqrt(variance.getResult());
        Assert.assertTrue(Math.abs(mean - 5.) < 1.e-3);
        Assert.assertTrue(Math.abs(observedSigma - .1) < 1.e-3);
    }
}

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From source file:Main.java

static double ATanH(double x) {
    return (0.5 * Math.log((1 + x) / (1 - x)));
}

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From source file:Main.java

static double LOGB2(double v) {
    return Math.log(v) / Math.log(2);
}

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From source file:Main.java

public static int merkleLevels(long x) {
    Double tmp = (Math.log(x) / Math.log(2));
    if (tmp - ((int) (0 + tmp)) > 0.0) {
        return (int) (tmp + 1);
    } else {/*from w w w  .  jav  a2s.  c o m*/
        return (int) (0 + tmp);
    }
}

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From source file:Main.java

private static double zoom(int mapPx, int worldPx, double fraction) {
    return Math.floor(Math.log(mapPx / worldPx / fraction) / LN2);
}

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From source file:Main.java

public static String doFormatarTamanho(long bytes) {
    int unit = 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("%.1f %sB", bytes / Math.pow(unit, exp), pre);
}

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