Examples with MathContext java.math.MathContext used on opensource projects

Example 66 with MathContext

use of java.math.MathContext in project big-math by eobermuhlner.

the class BigDecimalMath method logUsingTwoThree.

private static BigDecimal logUsingTwoThree(BigDecimal x, MathContext mathContext) {
    MathContext mc = new MathContext(mathContext.getPrecision() * 19 / 10 + 10, mathContext.getRoundingMode());
    // System.out.println("logUsingTwoThree(" + x + " " + mathContext + ") precision " + mc);
    int factorOfTwo = 0;
    int powerOfTwo = 1;
    int factorOfThree = 0;
    int powerOfThree = 1;
    double value = x.doubleValue();
    if (value < 0.01) {
    // do nothing
    } else if (value < 0.1) {
        // never happens when called by logUsingExponent()
        while (value < 0.6) {
            value *= 2;
            factorOfTwo--;
            powerOfTwo *= 2;
        }
    } else if (value < 0.115) {
        // (0.1 - 0.11111 - 0.115) -> (0.9 - 1.0 - 1.035)
        factorOfThree = -2;
        powerOfThree = 9;
    } else if (value < 0.14) {
        // (0.115 - 0.125 - 0.14) -> (0.92 - 1.0 - 1.12)
        factorOfTwo = -3;
        powerOfTwo = 8;
    } else if (value < 0.2) {
        // (0.14 - 0.16667 - 0.2) - (0.84 - 1.0 - 1.2)
        factorOfTwo = -1;
        powerOfTwo = 2;
        factorOfThree = -1;
        powerOfThree = 3;
    } else if (value < 0.3) {
        // (0.2 - 0.25 - 0.3) -> (0.8 - 1.0 - 1.2)
        factorOfTwo = -2;
        powerOfTwo = 4;
    } else if (value < 0.42) {
        // (0.3 - 0.33333 - 0.42) -> (0.9 - 1.0 - 1.26)
        factorOfThree = -1;
        powerOfThree = 3;
    } else if (value < 0.7) {
        // (0.42 - 0.5 - 0.7) -> (0.84 - 1.0 - 1.4)
        factorOfTwo = -1;
        powerOfTwo = 2;
    } else if (value < 1.4) {
    // (0.7 - 1.0 - 1.4) -> (0.7 - 1.0 - 1.4)
    // do nothing
    } else if (value < 2.5) {
        // (1.4 - 2.0 - 2.5) -> (0.7 - 1.0 - 1.25)
        factorOfTwo = 1;
        powerOfTwo = 2;
    } else if (value < 3.5) {
        // (2.5 - 3.0 - 3.5) -> (0.833333 - 1.0 - 1.166667)
        factorOfThree = 1;
        powerOfThree = 3;
    } else if (value < 5.0) {
        // (3.5 - 4.0 - 5.0) -> (0.875 - 1.0 - 1.25)
        factorOfTwo = 2;
        powerOfTwo = 4;
    } else if (value < 7.0) {
        // (5.0 - 6.0 - 7.0) -> (0.833333 - 1.0 - 1.166667)
        factorOfThree = 1;
        powerOfThree = 3;
        factorOfTwo = 1;
        powerOfTwo = 2;
    } else if (value < 8.5) {
        // (7.0 - 8.0 - 8.5) -> (0.875 - 1.0 - 1.0625)
        factorOfTwo = 3;
        powerOfTwo = 8;
    } else if (value < 10.0) {
        // (8.5 - 9.0 - 10.0) -> (0.94444 - 1.0 - 1.11111)
        factorOfThree = 2;
        powerOfThree = 9;
    } else {
        while (value > 1.4) {
            // never happens when called by logUsingExponent()
            value /= 2;
            factorOfTwo++;
            powerOfTwo *= 2;
        }
    }
    BigDecimal correctedX = x;
    BigDecimal result = ZERO;
    if (factorOfTwo > 0) {
        correctedX = correctedX.divide(valueOf(powerOfTwo), mc);
        result = result.add(logTwo(mc).multiply(valueOf(factorOfTwo), mc), mc);
    } else if (factorOfTwo < 0) {
        correctedX = correctedX.multiply(valueOf(powerOfTwo), mc);
        result = result.subtract(logTwo(mc).multiply(valueOf(-factorOfTwo), mc), mc);
    }
    if (factorOfThree > 0) {
        correctedX = correctedX.divide(valueOf(powerOfThree), mc);
        result = result.add(logThree(mc).multiply(valueOf(factorOfThree), mc), mc);
    } else if (factorOfThree < 0) {
        correctedX = correctedX.multiply(valueOf(powerOfThree), mc);
        result = result.subtract(logThree(mc).multiply(valueOf(-factorOfThree), mc), mc);
    }
    if (x == correctedX && result == ZERO) {
        return logUsingNewton(x, mathContext);
    }
    result = result.add(logUsingNewton(correctedX, mc), mc);
    return result;
}

Example 67 with MathContext

use of java.math.MathContext in project big-math by eobermuhlner.

the class BigDecimalMath method acot.

/**
 * Calculates the inverse cotangens (arc cotangens) of {@link BigDecimal} x.
 *
 * <p>See: <a href="http://en.wikipedia.org/wiki/Arccotangens">Wikipedia: Arccotangens</a></p>
 *
 * @param x the {@link BigDecimal} to calculate the arc cotangens for
 * @param mathContext the {@link MathContext} used for the result
 * @return the calculated arc cotangens {@link BigDecimal} with the precision specified in the <code>mathContext</code>
 */
public static BigDecimal acot(BigDecimal x, MathContext mathContext) {
    MathContext mc = new MathContext(mathContext.getPrecision() + 4, mathContext.getRoundingMode());
    BigDecimal result = pi(mc).divide(TWO, mc).subtract(atan(x, mc), mc);
    return result.round(mathContext);
}

Example 68 with MathContext

use of java.math.MathContext in project big-math by eobermuhlner.

the class BigDecimalMath method cot.

/**
 * Calculates the cotangens of {@link BigDecimal} x.
 *
 * <p>See: <a href="http://en.wikipedia.org/wiki/Cotangens">Wikipedia: Cotangens</a></p>
 *
 * @param x the {@link BigDecimal} to calculate the cotangens for
 * @param mathContext the {@link MathContext} used for the result
 * @return the calculated cotanges {@link BigDecimal} with the precision specified in the <code>mathContext</code>
 * @throws ArithmeticException if x = 0
 */
public static BigDecimal cot(BigDecimal x, MathContext mathContext) {
    if (x.signum() == 0) {
        throw new ArithmeticException("Illegal cot(x) for x = 0");
    }
    MathContext mc = new MathContext(mathContext.getPrecision() + 4, mathContext.getRoundingMode());
    BigDecimal result = cos(x, mc).divide(sin(x, mc), mc).round(mathContext);
    return result.round(mathContext);
}

Example 69 with MathContext

use of java.math.MathContext in project big-math by eobermuhlner.

the class BigDecimalMath method atanh.

/**
 * Calculates the arc hyperbolic tangens (inverse hyperbolic tangens ) of {@link BigDecimal} x.
 *
 * <p>See: <a href="https://en.wikipedia.org/wiki/Hyperbolic_function">Wikipedia: Hyperbolic function</a></p>
 *
 * @param x the {@link BigDecimal} to calculate the arc hyperbolic tanges for
 * @param mathContext the {@link MathContext} used for the result
 * @return the calculated arc hyperbolic tangens {@link BigDecimal} with the precision specified in the <code>mathContext</code>
 */
public static BigDecimal atanh(BigDecimal x, MathContext mathContext) {
    MathContext mc = new MathContext(mathContext.getPrecision() + 6, mathContext.getRoundingMode());
    BigDecimal result = log(ONE.add(x, mc).divide(ONE.subtract(x, mc), mc), mc).divide(TWO, mc);
    return result.round(mathContext);
}

Example 70 with MathContext

use of java.math.MathContext in project big-math by eobermuhlner.

the class BigDecimalMath method pow.

/**
 * Calculates {@link BigDecimal} x to the power of {@link BigDecimal} y (x<sup>y</sup>).
 *
 * @param x the {@link BigDecimal} value to take to the power
 * @param y the {@link BigDecimal} value to serve as exponent
 * @param mathContext the {@link MathContext} used for the result
 * @return the calculated x to the power of y with the precision specified in the <code>mathContext</code>
 */
public static BigDecimal pow(BigDecimal x, BigDecimal y, MathContext mathContext) {
    if (x.signum() == 0) {
        switch(y.signum()) {
            case 0:
                return ONE;
            case 1:
                return ZERO;
        }
    }
    try {
        long longValue = y.longValueExact();
        return pow(x, longValue, mathContext);
    } catch (ArithmeticException ex) {
    // ignored
    }
    if (fractionalPart(y).signum() == 0) {
        return powInteger(x, y, mathContext);
    }
    // x^y = exp(y*log(x))
    MathContext mc = new MathContext(mathContext.getPrecision() + 6, mathContext.getRoundingMode());
    BigDecimal result = exp(y.multiply(log(x, mc), mc), mc);
    return result.round(mathContext);
}