java.math
Class Multiplication

java.lang.Object
  java.math.Multiplication

 class Multiplication
extends Object

Static library that provides all multiplication of BigInteger methods.

Field Summary

(package private) static BigInteger[]	bigFivePows An array with the first powers of five in BigInteger version.
(package private) static BigInteger[]	bigTenPows An array with the first powers of ten in BigInteger version.
(package private) static int[]	fivePows An array with powers of five that fit in the type int.
(package private) static int[]	tenPows An array with powers of ten that fit in the type int.

Method Summary

(package private) static BigInteger	multiplyByFivePow(BigInteger val, int exp) Multiplies a number by a power of five.
(package private) static BigInteger	multiplyByPositiveInt(BigInteger val, int factor) Multiplies a number by a positive integer.
(package private) static BigInteger	multiplyByTenPow(BigInteger val, long exp) Multiplies a number by a power of ten.
(package private) static BigInteger	powerOf10(long exp) It calculates a power of ten, which exponent could be out of 32-bit range.

Methods inherited from class java.lang.Object

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

Field Detail

tenPows

static final int[] tenPows

An array with powers of ten that fit in the type int. (10^0,10^1,...,10^9)

fivePows

static final int[] fivePows

An array with powers of five that fit in the type int. (5^0,5^1,...,5^13)

bigTenPows

static final BigInteger[] bigTenPows

An array with the first powers of ten in BigInteger version. (10^0,10^1,...,10^31)

bigFivePows

static final BigInteger[] bigFivePows

An array with the first powers of five in BigInteger version. (5^0,5^1,...,5^31)

Method Detail

multiplyByPositiveInt

static BigInteger multiplyByPositiveInt(BigInteger val,
                                        int factor)

Multiplies a number by a positive integer.

Parameters:

val - an arbitrary BigInteger

factor - a positive int number

Returns:

val * factor

multiplyByTenPow

static BigInteger multiplyByTenPow(BigInteger val,
                                   long exp)

Multiplies a number by a power of ten. This method is used in BigDecimal class.

Parameters:

val - the number to be multiplied

exp - a positive long exponent

Returns:

val * 10<sup>exp</sup>

powerOf10

static BigInteger powerOf10(long exp)

It calculates a power of ten, which exponent could be out of 32-bit range. Note that internally this method will be used in the worst case with an exponent equals to: Integer.MAX_VALUE - Integer.MIN_VALUE.

Parameters:

exp - the exponent of power of ten, it must be positive.

Returns:

a BigInteger with value 10<sup>exp</sup>.

multiplyByFivePow

static BigInteger multiplyByFivePow(BigInteger val,
                                    int exp)

Multiplies a number by a power of five. This method is used in BigDecimal class.

Parameters:

val - the number to be multiplied

exp - a positive int exponent

Returns:

val * 5<sup>exp</sup>