water.util

Class MathUtils

java.lang.Object

water.util.MathUtils

public class MathUtils
extends java.lang.Object

Field Summary

Fields

Modifier and Type	Field and Description
static long[]	PRIMES

Constructor Summary

Constructors

Constructor and Description
MathUtils()

Method Summary

Methods

Modifier and Type	Method and Description
static double	approxExp(double x) Fast approximate exp
static double	approxInvSqrt(double x) Fast approximate 1./sqrt
static float	approxInvSqrt(float x) Fast approximate 1./sqrt
static double	approxLog(double x) Fast approximate log for values greater than 1, otherwise exact
static double	approxSqrt(double x) Fast approximate sqrt
static float	approxSqrt(float x) Fast approximate sqrt
static float	approxSumSquares(float[] a, int from, int to) Approximate sumSquares
static boolean	equalsWithinOneSmallUlp(double a, double b)
static boolean	equalsWithinOneSmallUlp(float a, float b) Compare two numbers to see if they are within one ulp of the smaller decade.
static double	innerProduct(double[] x, double[] y)
static double	l1norm(double[] x)
static double	l2norm(double[] x)
static double	l2norm2(double[] x)
static int	log2(int n) Fast calculation of log base 2 for integers.
static float	sumSquares(float[] a)
static float	sumSquares(float[] a, int from, int to)
static double[]	wadd(double[] x, double[] y, double w)

Methods inherited from class java.lang.Object

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

Field Detail

PRIMES

public static final long[] PRIMES

Constructor Detail

MathUtils

public MathUtils()

Method Detail

approxSqrt

public static final double approxSqrt(double x)

Fast approximate sqrt

Parameters:

x -

Returns:

sqrt(x) with up to 5% relative error

approxSqrt

public static final float approxSqrt(float x)

Fast approximate sqrt

Parameters:

x -

Returns:

sqrt(x) with up to 5% relative error

approxInvSqrt

public static final double approxInvSqrt(double x)

Fast approximate 1./sqrt

Parameters:

x -

Returns:

1./sqrt(x) with up to 2% relative error

approxInvSqrt

public static final float approxInvSqrt(float x)

Fast approximate 1./sqrt

Parameters:

x -

Returns:

1./sqrt(x) with up to 2% relative error

approxExp

public static final double approxExp(double x)

Fast approximate exp

Parameters:

x -

Returns:

exp(x) with up to 5% relative error

approxLog

public static final double approxLog(double x)

Fast approximate log for values greater than 1, otherwise exact

Parameters:

x -

Returns:

log(x) with up to 0.1% relative error

log2

public static final int log2(int n)

Fast calculation of log base 2 for integers.

Parameters:

n -

Returns:

log base 2 of n

sumSquares

public static float sumSquares(float[] a)

approxSumSquares

public static float approxSumSquares(float[] a,
                     int from,
                     int to)

Approximate sumSquares

Parameters:

a - Array with numbers

from - starting index (inclusive)

to - ending index (exclusive)

Returns:

approximate sum of squares based on a sample somewhere in the middle of the array (pos determined by bits of a[0])

sumSquares

public static float sumSquares(float[] a,
               int from,
               int to)

equalsWithinOneSmallUlp

public static boolean equalsWithinOneSmallUlp(float a,
                              float b)

Compare two numbers to see if they are within one ulp of the smaller decade. Order of the arguments does not matter.

Parameters:

a - First number

b - Second number

Returns:

true if a and b are essentially equal, false otherwise.

equalsWithinOneSmallUlp

public static boolean equalsWithinOneSmallUlp(double a,
                              double b)

innerProduct

public static final double innerProduct(double[] x,
                  double[] y)

l2norm2

public static final double l2norm2(double[] x)

l1norm

public static final double l1norm(double[] x)

l2norm

public static final double l2norm(double[] x)

wadd

public static final double[] wadd(double[] x,
            double[] y,
            double w)