cds.healpix.common.math

Class FastMath

java.lang.Object

cds.healpix.common.math.FastMath

public final class FastMath
extends java.lang.Object

Comes from the Apache FastMath class, and is thus under the Apache licence.

Author:

F.-X. Pineau

Field Summary

Fields

Modifier and Type	Field and Description
static double	SAFE_MIN

Constructor Summary

Constructors

Constructor and Description
FastMath()

Method Summary

Modifier and Type	Method and Description
static double	acos(double x) Compute the arc cosine of a number.
static double	asin(double x) Compute the arc sine of a number.
static double	atan(double x) Arctangent function
static double	copySign(double magnitude, double sign) Returns the first argument with the sign of the second argument.
static double	cosQ(double xa) Compute cosine in the first quadrant by subtracting input from PI/2 and then calling sinQ.
static double	sinQ(double xa, double xb) Compute sine over the first quadrant (0 < x < pi/2).
static double	sqrt(double a) Compute the square root of a number.

Methods inherited from class java.lang.Object

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

Field Detail

SAFE_MIN

public static final double SAFE_MIN

See Also:

Constant Field Values

Constructor Detail

FastMath

public FastMath()

Method Detail

sinQ

public static double sinQ(double xa,
                          double xb)

Compute sine over the first quadrant (0 < x < pi/2). Use combination of table lookup and rational polynomial expansion.

Parameters:

xa - number from which sine is requested

xb - second param

Returns:

sin(xa + xb)

cosQ

public static double cosQ(double xa)

Compute cosine in the first quadrant by subtracting input from PI/2 and then calling sinQ. This is more accurate as the input approaches PI/2.

Parameters:

xa - number from which cosine is requested

Returns:

cos(xa + xb)

asin

public static double asin(double x)

Compute the arc sine of a number.

Parameters:

x - number on which evaluation is done

Returns:

arc sine of x

atan

public static double atan(double x)

Arctangent function

Parameters:

x - a number

Returns:

atan(x)

acos

public static double acos(double x)

Compute the arc cosine of a number.

Parameters:

x - number on which evaluation is done

Returns:

arc cosine of x

sqrt

public static double sqrt(double a)

Compute the square root of a number.

Note: this implementation currently delegates to Math.sqrt(double)

Parameters:

a - number on which evaluation is done

Returns:

square root of a

copySign

public static double copySign(double magnitude,
                              double sign)

Returns the first argument with the sign of the second argument. A NaN sign argument is treated as positive.

Parameters:

magnitude - the value to return

sign - the sign for the returned value

Returns:

the magnitude with the same sign as the sign argument