com.numericalmethod.suanshu.number.big

Class BigDecimalUtils

java.lang.Object

com.numericalmethod.suanshu.number.big.BigDecimalUtils

public class BigDecimalUtils
extends java.lang.Object

These are the utility functions to manipulate BigDecimal.

See Also:

Class BigDecimal

Field Summary

Fields

Modifier and Type	Field and Description
static java.math.BigDecimal	PI the value of PI

Method Summary

Modifier and Type	Method and Description
static int	compare(java.math.BigDecimal n1, java.math.BigDecimal n2, int p) Compare two BigDecimals up to a precision.
static boolean	equals(java.math.BigDecimal n1, java.math.BigDecimal n2, int precision) Check if two BigDecimals are equal up to a precision.
static java.math.BigDecimal	exp(java.math.BigDecimal x) Compute ex.
static java.math.BigDecimal	exp(java.math.BigDecimal x, int scale) Compute ex.
static java.math.BigDecimal	exp(double x) Compute ex.
static java.math.BigDecimal	exp(double x, int scale) Compute ex.
static java.math.BigDecimal	getFractional(java.math.BigDecimal num) Get the fractional part of a number.
static java.math.BigDecimal	getWhole(java.math.BigDecimal num) Get the integral part of a number (discarding the fractional part).
static java.math.BigDecimal	log(java.math.BigDecimal x) Compute log(x).
static java.math.BigDecimal	log(java.math.BigDecimal x, int scale) Compute log(x) up to a scale.
static java.math.BigDecimal	pow(java.math.BigDecimal a, java.math.BigDecimal b) Compute a to the power of b.
static java.math.BigDecimal	pow(java.math.BigDecimal a, java.math.BigDecimal b, int scale) Compute a to the power of b.
static java.math.BigDecimal	pow(java.math.BigDecimal a, int n) Compute a to the power of n, where n is an integer.
static java.math.BigDecimal	pow(java.math.BigDecimal a, int n, int scale) Compute a to the power of n, where n is an integer.
static java.math.BigDecimal	sum(java.math.BigDecimal... big) Sum up the BigDecimal numbers.
static java.math.BigDecimal	sum(double... big) Sum up big numbers.

Methods inherited from class java.lang.Object

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

Field Detail

PI

public static final java.math.BigDecimal PI

the value of PI

See Also:

Joy of PI

Method Detail

compare

public static int compare(java.math.BigDecimal n1,
                          java.math.BigDecimal n2,
                          int p)

Compare two BigDecimals up to a precision. In other words, if the absolute difference between the two numbers falls below a threshold, they are considered equal.

Parameters:

n1 - a BigDecimal

n2 - a BigDecimal

p - the threshold is 1e-p

Returns:

-1, 0, or 1 when n1 is numerically less than, equal to, or greater than n2, respectively

equals

public static boolean equals(java.math.BigDecimal n1,
                             java.math.BigDecimal n2,
                             int precision)

Check if two BigDecimals are equal up to a precision.

Parameters:

n1 - a BigDecimal

n2 - a BigDecimal

precision - the threshold is 1e-p

Returns:

true if the numbers are equal up to a precision

sum

public static java.math.BigDecimal sum(java.math.BigDecimal... big)

Sum up the BigDecimal numbers.

Parameters:

big - BigDecimal numbers

Returns:

the sum

sum

public static java.math.BigDecimal sum(double... big)

Sum up big numbers.

Parameters:

big - numbers

Returns:

the sum

getWhole

public static java.math.BigDecimal getWhole(java.math.BigDecimal num)

Get the integral part of a number (discarding the fractional part).

Parameters:

num - a BigDecimal

Returns:

the integral part of the number

getFractional

public static java.math.BigDecimal getFractional(java.math.BigDecimal num)

Get the fractional part of a number. This is the same as the number subtracting the whole part. For a -ve. number, the fractional part is also -ve. For example, for -3.1415, the whole is -3 and the fractional part is -0.1415.

Parameters:

num - a BigDecimal

Returns:

the fractional part of the number

pow

public static java.math.BigDecimal pow(java.math.BigDecimal a,
                                       java.math.BigDecimal b)

Compute a to the power of b.

Parameters:

a - a base

b - an exponent

Returns:

a^b

pow

public static java.math.BigDecimal pow(java.math.BigDecimal a,
                                       java.math.BigDecimal b,
                                       int scale)

Compute a to the power of b.

Parameters:

a - a base

b - an exponent

scale - a precision parameter as in BigDecimal

Returns:

a^b

pow

public static java.math.BigDecimal pow(java.math.BigDecimal a,
                                       int n)

Compute a to the power of n, where n is an integer.

Parameters:

a - a base

n - an integer exponent

Returns:

aⁿ

pow

public static java.math.BigDecimal pow(java.math.BigDecimal a,
                                       int n,
                                       int scale)

Compute a to the power of n, where n is an integer. This is simply a wrapper around BigDecimal.pow(int) but handles also negative exponents. Use BigDecimal.pow(int) for arbitrary precision if the exponent is positive.

Parameters:

a - a base

n - an exponent

scale - a precision parameter as in BigDecimal

Returns:

aⁿ

log

public static java.math.BigDecimal log(java.math.BigDecimal x)

Compute log(x). The base is e, hence the natural log.

Parameters:

x - a number

Returns:

log(x)

See Also:

Wikipedia: Natural logarithm

log

public static java.math.BigDecimal log(java.math.BigDecimal x,
                                       int scale)

Compute log(x) up to a scale. The base is e, hence the natural log.

Parameters:

x - a number

scale - a precision parameter as in BigDecimal

Returns:

log(x)

See Also:

Wikipedia: Natural logarithm

exp

public static java.math.BigDecimal exp(double x)

Compute e^x.

Parameters:

x - the exponent

Returns:

e^x

See Also:

Wikipedia: Exponential function

exp

public static java.math.BigDecimal exp(double x,
                                       int scale)

Compute e^x.

Parameters:

x - the exponent

scale - a precision parameter as in BigDecimal

Returns:

e^x

See Also:

Wikipedia: Exponential function

exp

public static java.math.BigDecimal exp(java.math.BigDecimal x)

Compute e^x.

Parameters:

x - the exponent

Returns:

e^x

See Also:

Wikipedia: Exponential function

exp

public static java.math.BigDecimal exp(java.math.BigDecimal x,
                                       int scale)

Compute e^x.

Parameters:

x - the exponent

scale - a precision parameter as in BigDecimal

Returns:

e^x

See Also:

Wikipedia: Exponential function