Package es.upm.etsisi.cf4j.util

Class Maths

java.lang.Object

es.upm.etsisi.cf4j.util.Maths

public class Maths
extends Object

This class contains useful math methods.

Constructor Summary

Constructors

Constructor	Description
Maths()

Method Summary

Modifier and Type	Method	Description
static double	arrayAverage(double[] array)	Calculates the average of an double array
static double	arrayAverage(int[] array)	Calculates the average of an int array
static double	arrayStandardDeviation(double[] array)	Calculates the standard deviation of an double array
static double	arrayStandardDeviation(int[] array)	Calculate the standard deviation of an int array
static double	dotProduct(double[] a, double[] b)	Dot product between two vectors
static double[]	linespace(double start, double stop, int num)	Returns num evenly spaced samples.
static double[]	linespace(double start, double stop, int num, boolean endpoint)	Returns num evenly spaced samples.
static double[]	linespace(double stop, int num)	Returns num evenly spaced samples.
static double	log(double x, double b)	Returns the log in an specific base
static double	logistic(double x)	Returns the logistic function g(x)
static double[]	logspace(double start, double stop, int num)	Return numbers spaced evenly on a log scale.
static double[]	logspace(double start, double stop, int num, boolean endpoint)	Return numbers spaced evenly on a log scale.
static double[]	logspace(double start, double stop, int num, boolean endpoint, double base)	Return numbers spaced evenly on a log scale.
static double[]	logspace(double start, double stop, int num, double base)	Return numbers spaced evenly on a log scale.
static int[]	range(int stop)	Returns an array of int values.
static int[]	range(int start, int stop)	Returns an array of int values.
static int[]	range(int start, int stop, int step)	Returns an array of int values.
static int[]	range(int start, int stop, int step, boolean endpoint)	Returns an array of int values.

Methods inherited from class java.lang.Object

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

Constructor Detail

Maths

public Maths()

Method Detail

arrayAverage

public static double arrayAverage(double[] array)

Calculates the average of an double array

Parameters:

array - Array of double from which to calculate the mean

Returns:

Array mean

arrayStandardDeviation

public static double arrayStandardDeviation(double[] array)

Calculates the standard deviation of an double array

Parameters:

array - Array of double from which to calculate the standard deviation

Returns:

Standard deviation of the array

arrayAverage

public static double arrayAverage(int[] array)

Calculates the average of an int array

Parameters:

array - Array of int from which to calculate the mean

Returns:

Array mean

arrayStandardDeviation

public static double arrayStandardDeviation(int[] array)

Calculate the standard deviation of an int array

Parameters:

array - Array of int from which to calculate the standard deviation

Returns:

Standard deviation of the array

dotProduct

public static double dotProduct(double[] a,
                                double[] b)

Dot product between two vectors

Parameters:

a - Vector A

b - Vector B

Returns:

dot_product(A, B)

log

public static double log(double x,
                         double b)

Returns the log in an specific base

Parameters:

x - Value

b - Base

Returns:

log of x in base b

logistic

public static double logistic(double x)

Returns the logistic function g(x)

Parameters:

x - The given parameter x of the function g(x)

Returns:

Value of the logistic function g(x)

range

public static int[] range(int start,
                          int stop,
                          int step,
                          boolean endpoint)

Returns an array of int values.

Parameters:

start - An integer value specifying at which position to start. Default 0.

stop - An integer value specifying at which position to stop.

step - An integer value specifying the incrementation. Default 1.

endpoint - If true, include the stop value. Otherwise, it is not included. Default true.

Returns:

Values of the range.

range

public static int[] range(int start,
                          int stop,
                          int step)

Returns an array of int values.

Parameters:

start - An integer value specifying at which position to start. Default 0.

stop - An integer value specifying at which position to stop.

step - An integer value specifying the incrementation. Default 1.

Returns:

Values of the range.

range

public static int[] range(int start,
                          int stop)

Returns an array of int values.

Parameters:

start - An integer value specifying at which position to start. Default 0.

stop - An integer value specifying at which position to stop.

Returns:

Values of the range.

range

public static int[] range(int stop)

Returns an array of int values.

Parameters:

stop - An integer value specifying at which position to stop.

Returns:

Values of the range.

linespace

public static double[] linespace(double start,
                                 double stop,
                                 int num,
                                 boolean endpoint)

Returns num evenly spaced samples.

Parameters:

start - The starting value. Default 0.0.

stop - The stop value.

num - Number of samples to generate.

endpoint - If true, stop is the last sample. Otherwise, it is not included. Default true.

Returns:

Double array with num evenly spaced samples.

linespace

public static double[] linespace(double start,
                                 double stop,
                                 int num)

Returns num evenly spaced samples.

Parameters:

start - The starting value. Default 0.0.

stop - The stop value.

num - Number of samples to generate.

Returns:

Double array with num evenly spaced samples.

linespace

public static double[] linespace(double stop,
                                 int num)

Returns num evenly spaced samples.

Parameters:

stop - The stop value.

num - Number of samples to generate.

Returns:

Double array with num evenly spaced samples.

logspace

public static double[] logspace(double start,
                                double stop,
                                int num,
                                boolean endpoint,
                                double base)

Return numbers spaced evenly on a log scale. The sequence starts at Math.pow(base, start).

Parameters:

start - Math.pow(base, start) is the starting value of the sequence.

stop - Math.pow(base, stop) is the last value of the sequence if endpoint is true.

num - Number of samples to generate.

endpoint - If true, stop is the last sample. Otherwise, it is not included. Default true.

base - The base of the log space. Default 10.

Returns:

Double array with num evenly spaced samples on a log scale.

logspace

public static double[] logspace(double start,
                                double stop,
                                int num,
                                boolean endpoint)

Return numbers spaced evenly on a log scale. The sequence starts at Math.pow(base, start).

Parameters:

start - Math.pow(base, start) is the starting value of the sequence.

stop - Math.pow(base, stop) is the last value of the sequence if endpoint is true.

num - Number of samples to generate.

endpoint - If true, stop is the last sample. Otherwise, it is not included. Default true.

Returns:

Double array with num evenly spaced samples on a log scale.

logspace

public static double[] logspace(double start,
                                double stop,
                                int num,
                                double base)

Return numbers spaced evenly on a log scale. The sequence starts at Math.pow(base, start).

Parameters:

start - Math.pow(base, start) is the starting value of the sequence.

stop - Math.pow(base, stop) is the last value of the sequence if endpoint is true.

num - Number of samples to generate.

base - The base of the log space. Default 10.

Returns:

Double array with num evenly spaced samples on a log scale.

logspace

public static double[] logspace(double start,
                                double stop,
                                int num)

Return numbers spaced evenly on a log scale. The sequence starts at Math.pow(base, start).

Parameters:

start - Math.pow(base, start) is the starting value of the sequence.

stop - Math.pow(base, stop) is the last value of the sequence if endpoint is true.

num - Number of samples to generate.

Returns:

Double array with num evenly spaced samples on a log scale.