org.znerd.math
Class DigitSet

java.lang.Object
  |
  +--java.lang.Number
        |
        +--org.znerd.math.RealNumber
              |
              +--org.znerd.math.RationalNumber
                    |
                    +--org.znerd.math.DigitSet

Direct Known Subclasses:

BasicDigitSet

public abstract class DigitSet

extends RationalNumber

A set of digits, having a radix and an exponent. Objects of this type are used to implement rounding.

The value of a DigitSet number is the sum of:

digits[0] * radix^exponent
digits[1] * radix^{exponent - 1}
digits[2] * radix^{exponent - 2}
...
digits[precision - 1] * radix^{exponent - (precision - 1)}

Version:

$Revision: 1.11 $ $Date: 2002/08/16 21:54:40 $

Author:

Ernst de Haan (znerd@FreeBSD.org)

See Also:

Serialized Form

Fields inherited from class org.znerd.math.RealNumber

MAXIMUM_RADIX

Constructor Summary

protected

DigitSet(IntegerNumber[] parts, String asString) Creates a new DigitSet instance.

Method Summary

abstract int[]	getDigits() Returns a new array containing all the digits.
abstract int	getExponent() Returns the exponent.
abstract int	getPrecision() Returns the precision, the total number of digits.
abstract int	getRadix() Returns the radix or base.
DigitSet	toPrecision(int precision) Returns a digit set with the specified precision.
protected abstract DigitSet	toPrecisionImpl(int precision) Returns a digit set with the specified precision, actual implementation.

Methods inherited from class org.znerd.math.RationalNumber

add, add, compareTo, compareToImpl, compareToImpl, compareToImpl2, divide, divide, doubleValue, getDenominator, getNumerator, invert, multiply, multiply, negate, pow, pow, subtract, subtract, toBigDecimal, toBigDecimal, trunc

Methods inherited from class org.znerd.math.RealNumber

abs, byteValue, compareTo, compareTo, equals, fitsByte, fitsDouble, fitsFloat, fitsInt, fitsLong, fitsShort, floatValue, getSign, intValue, longValue, round, shortValue, toBigInteger, toString

Methods inherited from class java.lang.Object

clone, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

DigitSet

protected DigitSet(IntegerNumber[] parts,
                   String asString)
            throws IllegalArgumentException

Creates a new DigitSet instance.

Parameters:

parts - an array containing the numerator and denonimator, not null, having at least 2 elements and not having a null at index 0 or 1.

asString - textual presentation of this number, not null.

Throws:

IllegalArgumentException - if asString == null.

Method Detail

getRadix

public abstract int getRadix()

Returns the radix or base. The radix is for example 10 for a decimal number and 16 for a hexadecimal number. A binary number has the smallest radix, 2.

Returns:

the radix, always > 1.

getExponent

public abstract int getExponent()

Returns the exponent.

Returns:

the exponent.

getDigits

public abstract int[] getDigits()

Returns a new array containing all the digits. Every digit in the returned array is an int value between 0 (inclusive) and the radix (exclusive).

Returns:

a new array containing all the digits; r != null && r[i] >= 0 && r[i] < getRadix(), where r is the return value and i is an int between 0 and r.length.

getPrecision

public abstract int getPrecision()

Returns the precision, the total number of digits.

Returns:

the precision, always >= 0.

toPrecision

public final DigitSet toPrecision(int precision)
                           throws IllegalArgumentException

Returns a digit set with the specified precision. If the specified precision is larger than or equal to the current precision, then this digit set (this) will be returned.

No rounding will be performed, only truncation. If the specified precision is smaller than the precision of this DigitSet, then some of the digits will just be removed.

This method calls toPrecisionImpl(int) after checking the preconditions. If that method returns an invalid value, then an InternalError is thrown.

Parameters:

precision - the precision, >= 1.

Returns:

a DigitSet that is equal to this number, truncated to the specified precision, never null.

Throws:

IllegalArgumentException - if precision < 1.

toPrecisionImpl

protected abstract DigitSet toPrecisionImpl(int precision)

Returns a digit set with the specified precision, actual implementation. This method is called from toPrecision(int).

Parameters:

precision - the precision, guaranteed to be >= 1 and < getPrecision().

Returns:

a DigitSet that is equal to this number, truncated to the specified precision.