com.jidesoft.utils
Class MathUtils

java.lang.Object
  com.jidesoft.utils.MathUtils

public final class MathUtils
extends Object

A collection of several util methods related to Math. We only used it in DefaultSummaryCalculator in JIDE Pivot Grid to calculate statistics but this class will be reserved as a place holder for methods related to Math.

Constructor Summary

protected

MathUtils()

Method Summary

static double	max(List<Number> numbers) Returns the max number in the numbers list.
static double	mean(List<Number> numbers) Returns the mean number in the numbers list.
static double	min(List<Number> numbers) Returns the min number in the numbers list.
static double	stddev(List<Number> numbers, boolean biasCorrected) Returns the standard deviation of the numbers.
static double	sum(List<Number> numbers) Returns the sum number in the numbers list.
static double	var(List<Number> numbers, boolean biasCorrected) Computes the variance of the available values.

Methods inherited from class java.lang.Object

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

Constructor Detail

MathUtils

protected MathUtils()

Method Detail

sum

public static double sum(List<Number> numbers)

Returns the sum number in the numbers list.

Parameters:

numbers - the numbers to calculate the sum.

Returns:

the sum of the numbers.

mean

public static double mean(List<Number> numbers)

Returns the mean number in the numbers list.

Parameters:

numbers - the numbers to calculate the mean.

Returns:

the mean of the numbers.

min

public static double min(List<Number> numbers)

Returns the min number in the numbers list.

Parameters:

numbers - the numbers to calculate the min.

Returns:

the min number in the numbers list.

max

public static double max(List<Number> numbers)

Returns the max number in the numbers list.

Parameters:

numbers - the numbers to calculate the max.

Returns:

the max number in the numbers list.

stddev

public static double stddev(List<Number> numbers,
                            boolean biasCorrected)

Returns the standard deviation of the numbers.

Double.NaN is returned if the numbers list is empty.

Parameters:

numbers - the numbers to calculate the standard deviation.

biasCorrected - true if variance is calculated by dividing by n - 1. False if by n. stddev is a sqrt of the variance.

Returns:

the standard deviation

var

public static double var(List<Number> numbers,
                         boolean biasCorrected)

Computes the variance of the available values. By default, the unbiased "sample variance" definitional formula is used: variance = sum((x_i - mean)^2) / (n - 1)

The "population variance" ( sum((x_i - mean)^2) / n ) can also be computed using this statistic. The biasCorrected property determines whether the "population" or "sample" value is returned by the evaluate and getResult methods. To compute population variances, set this property to false.

Parameters:

numbers - the numbers to calculate the variance.

biasCorrected - true if variance is calculated by dividing by n - 1. False if by n.

Returns:

the variance of the numbers.