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

Example 71 with MathContext

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

the class BigDecimalMath method log2.

/**
 * Calculates the logarithm of {@link BigDecimal} x to the base 2.
 *
 * @param x the {@link BigDecimal} to calculate the logarithm base 2 for
 * @param mathContext the {@link MathContext} used for the result
 * @return the calculated natural logarithm {@link BigDecimal} to the base 2 with the precision specified in the <code>mathContext</code>
 * @throws ArithmeticException if x &lt;= 0
 */
public static BigDecimal log2(BigDecimal x, MathContext mathContext) {
    MathContext mc = new MathContext(mathContext.getPrecision() + 4, mathContext.getRoundingMode());
    BigDecimal result = log(x, mc).divide(logTwo(mc), mc);
    return result.round(mathContext);
}

Example 72 with MathContext

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

the class BigDecimalMath method powInteger.

/**
 * Calculates {@link BigDecimal} x to the power of the integer value y (x<sup>y</sup>).
 *
 * <p>The value y MUST be an integer value.</p>
 *
 * @param x the {@link BigDecimal} value to take to the power
 * @param integerY the {@link BigDecimal} <strong>integer</strong> 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>
 * @see #pow(BigDecimal, long, MathContext)
 */
private static BigDecimal powInteger(BigDecimal x, BigDecimal integerY, MathContext mathContext) {
    if (fractionalPart(integerY).signum() != 0) {
        throw new IllegalArgumentException("Not integer value: " + integerY);
    }
    if (integerY.signum() < 0) {
        return ONE.divide(powInteger(x, integerY.negate(), mathContext), mathContext);
    }
    MathContext mc = new MathContext(Math.max(mathContext.getPrecision(), -integerY.scale()) + 30, mathContext.getRoundingMode());
    BigDecimal result = ONE;
    while (integerY.signum() > 0) {
        BigDecimal halfY = integerY.divide(TWO, mc);
        if (fractionalPart(halfY).signum() != 0) {
            // odd exponent -> multiply result with x
            result = result.multiply(x, mc);
            integerY = integerY.subtract(ONE);
            halfY = integerY.divide(TWO, mc);
        }
        if (halfY.signum() > 0) {
            // even exponent -> square x
            x = x.multiply(x, mc);
        }
        integerY = halfY;
    }
    return result.round(mathContext);
}

Example 73 with MathContext

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

the class BigDecimalMath method acos.

/**
 * Calculates the arc cosine (inverted cosine) of {@link BigDecimal} x.
 *
 * <p>See: <a href="http://en.wikipedia.org/wiki/Arccosine">Wikipedia: Arccosine</a></p>
 *
 * @param x the {@link BigDecimal} to calculate the arc cosine for
 * @param mathContext the {@link MathContext} used for the result
 * @return the calculated arc sine {@link BigDecimal} with the precision specified in the <code>mathContext</code>
 * @throws ArithmeticException if x &gt; 1 or x &lt; -1
 */
public static BigDecimal acos(BigDecimal x, MathContext mathContext) {
    if (x.compareTo(ONE) > 0) {
        throw new ArithmeticException("Illegal acos(x) for x > 1: x = " + x);
    }
    if (x.compareTo(MINUS_ONE) < 0) {
        throw new ArithmeticException("Illegal acos(x) for x < -1: x = " + x);
    }
    MathContext mc = new MathContext(mathContext.getPrecision() + 6, mathContext.getRoundingMode());
    BigDecimal result = pi(mc).divide(TWO, mc).subtract(asin(x, mc), mc);
    return result.round(mathContext);
}

Example 74 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 <code>long</code> y (x<sup>y</sup>).
 *
 * <p>The implementation tries to minimize the number of multiplications of {@link BigDecimal x} (using squares whenever possible).</p>
 *
 * <p>See: <a href="https://en.wikipedia.org/wiki/Exponentiation#Efficient_computation_with_integer_exponents">Wikipedia: Exponentiation - efficient computation</a></p>
 *
 * @param x the {@link BigDecimal} value to take to the power
 * @param y the <code>long</code> 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, long y, MathContext mathContext) {
    MathContext mc = new MathContext(mathContext.getPrecision() + 10, mathContext.getRoundingMode());
    if (y < 0) {
        return ONE.divide(pow(x, -y, mc), mc).round(mathContext);
    }
    BigDecimal result = ONE;
    while (y > 0) {
        if ((y & 1) == 1) {
            // odd exponent -> multiply result with x
            result = result.multiply(x, mc);
            y -= 1;
        }
        if (y > 0) {
            // even exponent -> square x
            x = x.multiply(x, mc);
        }
        y >>= 1;
    }
    return result.round(mathContext);
}

Example 75 with MathContext

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

the class BigDecimalMath method sqrt.

/**
 * Calculates the square root of {@link BigDecimal} x.
 *
 * <p>See <a href="http://en.wikipedia.org/wiki/Square_root">Wikipedia: Square root</a></p>
 *
 * @param x the {@link BigDecimal} value to calculate the square root
 * @param mathContext the {@link MathContext} used for the result
 * @return the calculated square root of x with the precision specified in the <code>mathContext</code>
 * @throws ArithmeticException if x &lt; 0
 */
public static BigDecimal sqrt(BigDecimal x, MathContext mathContext) {
    switch(x.signum()) {
        case 0:
            return ZERO;
        case -1:
            throw new ArithmeticException("Illegal sqrt(x) for x < 0: x = " + x);
    }
    int maxPrecision = mathContext.getPrecision() + 6;
    BigDecimal acceptableError = ONE.movePointLeft(mathContext.getPrecision() + 1);
    BigDecimal result;
    if (isDoubleValue(x)) {
        result = BigDecimal.valueOf(Math.sqrt(x.doubleValue()));
    } else {
        result = x.divide(TWO, mathContext);
    }
    if (result.multiply(result, mathContext).compareTo(x) == 0) {
        // early exit if x is a square number
        return result.round(mathContext);
    }
    int adaptivePrecision = EXPECTED_INITIAL_PRECISION;
    BigDecimal last;
    do {
        last = result;
        adaptivePrecision = adaptivePrecision * 2;
        if (adaptivePrecision > maxPrecision) {
            adaptivePrecision = maxPrecision;
        }
        MathContext mc = new MathContext(adaptivePrecision, mathContext.getRoundingMode());
        result = x.divide(result, mc).add(last, mc).divide(TWO, mc);
    } while (adaptivePrecision < maxPrecision || result.subtract(last).abs().compareTo(acceptableError) > 0);
    return result.round(mathContext);
}