Example usage for java.math MathContext MathContext

Introduction

In this page you can find the example usage for java.math MathContext MathContext.

Prototype

public MathContext(int setPrecision, RoundingMode setRoundingMode)

Source Link

Document

Constructs a new MathContext with a specified precision and rounding mode.

Usage

From source file:Main.java

public static BigDecimal log10(BigDecimal b) {
    final int NUM_OF_DIGITS = SCALE + 2;
    // need to add one to get the right number of dp
    // and then add one again to get the next number
    // so I can round it correctly.

    MathContext mc = new MathContext(NUM_OF_DIGITS, RoundingMode.HALF_EVEN);
    // special conditions:
    // log(-x) -> exception
    // log(1) == 0 exactly;
    // log of a number lessthan one = -log(1/x)
    if (b.signum() <= 0) {
        throw new ArithmeticException("log of a negative number! (or zero)");
    } else if (b.compareTo(BigDecimal.ONE) == 0) {
        return BigDecimal.ZERO;
    } else if (b.compareTo(BigDecimal.ONE) < 0) {
        return (log10((BigDecimal.ONE).divide(b, mc))).negate();
    }/*from  ww  w.  java 2 s  .c  om*/

    StringBuilder sb = new StringBuilder();
    // number of digits on the left of the decimal point
    int leftDigits = b.precision() - b.scale();

    // so, the first digits of the log10 are:
    sb.append(leftDigits - 1).append(".");

    // this is the algorithm outlined in the webpage
    int n = 0;
    while (n < NUM_OF_DIGITS) {
        b = (b.movePointLeft(leftDigits - 1)).pow(10, mc);
        leftDigits = b.precision() - b.scale();
        sb.append(leftDigits - 1);
        n++;
    }

    BigDecimal ans = new BigDecimal(sb.toString());

    // Round the number to the correct number of decimal places.
    ans = ans.round(new MathContext(ans.precision() - ans.scale() + SCALE, RoundingMode.HALF_EVEN));
    return ans;
}

From source file:Main.java

public static BigDecimal log10(BigDecimal b) {
    final int NUM_OF_DIGITS = SCALE + 2;
    // need to add one to get the right number of dp
    //  and then add one again to get the next number
    //  so I can round it correctly.

    MathContext mc = new MathContext(NUM_OF_DIGITS, RoundingMode.HALF_EVEN);
    //special conditions:
    // log(-x) -> exception
    // log(1) == 0 exactly;
    // log of a number lessthan one = -log(1/x)
    if (b.signum() <= 0) {
        throw new ArithmeticException("log of a negative number! (or zero)");
    } else if (b.compareTo(BigDecimal.ONE) == 0) {
        return BigDecimal.ZERO;
    } else if (b.compareTo(BigDecimal.ONE) < 0) {
        return (log10((BigDecimal.ONE).divide(b, mc))).negate();
    }//from  ww w .  j  ava 2  s .c o  m

    StringBuilder sb = new StringBuilder();
    //number of digits on the left of the decimal point
    int leftDigits = b.precision() - b.scale();

    //so, the first digits of the log10 are:
    sb.append(leftDigits - 1).append(".");

    //this is the algorithm outlined in the webpage
    int n = 0;
    while (n < NUM_OF_DIGITS) {
        b = (b.movePointLeft(leftDigits - 1)).pow(10, mc);
        leftDigits = b.precision() - b.scale();
        sb.append(leftDigits - 1);
        n++;
    }

    BigDecimal ans = new BigDecimal(sb.toString());

    //Round the number to the correct number of decimal places.
    ans = ans.round(new MathContext(ans.precision() - ans.scale() + SCALE, RoundingMode.HALF_EVEN));
    return ans;
}

From source file:net.vexelon.bgrates.Utils.java

public static String roundNumber(BigDecimal number, int n) {
    return number.round(new MathContext(n, RoundingMode.HALF_UP)).toPlainString();
}

From source file:r.base.MathExt.java

@Primitive
public static double signif(@Recycle double x, @Recycle int digits) {
    return new BigDecimal(x).round(new MathContext(digits, RoundingMode.HALF_UP)).doubleValue();
}

From source file:org.renjin.MathExt.java

public static double signif(double x, int digits) {
    return new BigDecimal(x).round(new MathContext(digits, RoundingMode.HALF_UP)).doubleValue();
}

From source file:au.org.ala.delta.model.attribute.SignificantFiguresAttributeChunkFormatter.java

/**
 * Overrides formatNumber in the parent class to format the number to 5 significant figures.  Trailing
 * zeros are stripped./*from w ww .  j a v a 2  s.c  om*/
 * Note: for compatibility with the original CONFOR significant figures are only applied to values after
 * the decimal place. (e.g. 123456.7 will be formatted as 123456, not 123460)
 * @param number the number to format.
 * @return the supplied number as a String.
 */
@Override
public String formatNumber(BigDecimal number) {

    int significantFigures = determinePrecision(number);
    MathContext context = new MathContext(significantFigures, RoundingMode.HALF_UP);

    BigDecimal result = number.round(context);
    result = result.stripTrailingZeros();
    return result.toPlainString();
}

From source file:fuzzy.util.MaxMF.java

public Map<Double, Double> evaluate(Collection<T> x, MembershipFunction<T> mf) {
    Map<Double, Double> max = new HashMap<Double, Double>();
    BigDecimal maxValue = BigDecimal.valueOf(0.0);
    boolean first = true;
    for (T value : x) {
        BigDecimal temp = new BigDecimal(mf.evaluate(value), new MathContext(precision, roundingMode));
        if (first || temp.compareTo(maxValue) > 0) {
            first = false;/*from w  ww  .ja v a  2 s. c o m*/
            maxValue = temp;
            max.clear();
            max.put(value.doubleValue(), temp.doubleValue());
        } else if (temp.compareTo(maxValue) == 0) {
            max.put(value.doubleValue(), temp.doubleValue());
        } // else ignore since it's less than the maximum value
    }
    return max;
}

From source file:org.homiefund.test.dao.TransactionDAOTest.java

@Test
public void create() {
    Transaction tx = new Transaction();
    tx.setRevoked(false);/*from w  w  w  .j av a2  s  .com*/
    tx.setDate(LocalDate.now());
    tx.setDescription(" create tessst ");
    tx.setOwner(userDAO.getById(1L));
    tx.setTransactionType(transactionTypeDAO.getById(4L));
    tx.setAmount(BigDecimal.valueOf(30.52));
    TransactionParticipant tp1 = new TransactionParticipant();
    tp1.setParticipant(userDAO.getById(1L));
    TransactionParticipant tp2 = new TransactionParticipant();
    tp2.setParticipant(userDAO.getById(2L));
    tx.setParticipants(new ArrayList<>(Arrays.asList(tp1, tp2)));

    Assert.assertNotNull(transactionDAO.create(tx));
    Assert.assertNotNull(tx.getId());

    BigDecimal half = tx.getAmount().divide(BigDecimal.valueOf(2L), new MathContext(2, RoundingMode.HALF_UP));
    tx.getParticipants().forEach(p -> Assert.assertEquals(half, p.getAmount()));
}

From source file:org.renjin.primitives.MathExt.java

@Deferrable
@Builtin/* w w  w  .  jav a  2 s  . c  om*/
@DataParallel
public static double signif(double x, int digits) {
    return new BigDecimal(x).round(new MathContext(digits, RoundingMode.HALF_UP)).doubleValue();
}

From source file:com.ibk.ltw.domain.Product.java

/**
 *
 * @return Price with VAT/*  w w w  .  ja va2s  .  co m*/
 */
public int getGrossPriceInCents() {
    BigDecimal grossPriceInCents = new BigDecimal(netPriceInCents)
            .multiply(new BigDecimal(1000 + vatService.getVatInPerThousand())).movePointLeft(3);
    return grossPriceInCents.round(new MathContext(0, RoundingMode.HALF_UP)).intValue();
}