com.google.common.math
Class DoubleMath

java.lang.Object
  com.google.common.math.DoubleMath

@Beta
public final class DoubleMath
extends Object

A class for arithmetic on doubles that is not covered by Math.

Since:

11.0

Author:

Louis Wasserman

Method Summary

static double	factorial(int n) Returns n!, that is, the product of the first n positive integers, 1 if n == 0, or e n!}, or Double.POSITIVE_INFINITY if n! > Double.MAX_VALUE.
static boolean	isMathematicalInteger(double x) Returns true if x represents a mathematical integer.
static boolean	isPowerOfTwo(double x) Returns true if x is exactly equal to 2^k for some finite integer k.
static double	log2(double x) Returns the base 2 logarithm of a double value.
static int	log2(double x, RoundingMode mode) Returns the base 2 logarithm of a double value, rounded with the specified rounding mode to an int.
static BigInteger	roundToBigInteger(double x, RoundingMode mode) Returns the BigInteger value that is equal to x rounded with the specified rounding mode, if possible.
static int	roundToInt(double x, RoundingMode mode) Returns the int value that is equal to x rounded with the specified rounding mode, if possible.
static long	roundToLong(double x, RoundingMode mode) Returns the long value that is equal to x rounded with the specified rounding mode, if possible.

Methods inherited from class java.lang.Object

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

Method Detail

roundToInt

public static int roundToInt(double x,
                             RoundingMode mode)

Returns the int value that is equal to x rounded with the specified rounding mode, if possible.

Throws:

ArithmeticException - if

• x is infinite or NaN
• x, after being rounded to a mathematical integer using the specified rounding mode, is either less than Integer.MIN_VALUE or greater than Integer.MAX_VALUE
• x is not a mathematical integer and mode is RoundingMode.UNNECESSARY

roundToLong

public static long roundToLong(double x,
                               RoundingMode mode)

Returns the long value that is equal to x rounded with the specified rounding mode, if possible.

Throws:

ArithmeticException - if

• x is infinite or NaN
• x, after being rounded to a mathematical integer using the specified rounding mode, is either less than Long.MIN_VALUE or greater than Long.MAX_VALUE
• x is not a mathematical integer and mode is RoundingMode.UNNECESSARY

roundToBigInteger

public static BigInteger roundToBigInteger(double x,
                                           RoundingMode mode)

Returns the BigInteger value that is equal to x rounded with the specified rounding mode, if possible.

Throws:

ArithmeticException - if

• x is infinite or NaN
• x is not a mathematical integer and mode is RoundingMode.UNNECESSARY

isPowerOfTwo

public static boolean isPowerOfTwo(double x)

Returns true if x is exactly equal to 2^k for some finite integer k.

log2

public static double log2(double x)

Returns the base 2 logarithm of a double value.

Special cases:

• If x is NaN or less than zero, the result is NaN.
• If x is positive infinity, the result is positive infinity.
• If x is positive or negative zero, the result is negative infinity.

The computed result must be within 1 ulp of the exact result.

If the result of this method will be immediately rounded to an int, log2(double, RoundingMode) is faster.

log2

public static int log2(double x,
                       RoundingMode mode)

Returns the base 2 logarithm of a double value, rounded with the specified rounding mode to an int.

Regardless of the rounding mode, this is faster than (int) log2(x).

Throws:

IllegalArgumentException - if x <= 0.0, x is NaN, or x is infinite

isMathematicalInteger

public static boolean isMathematicalInteger(double x)

Returns true if x represents a mathematical integer.

This is equivalent to, but not necessarily implemented as, the expression !Double.isNaN(x) && !Double.isInfinite(x) && x == Math.rint(x).

factorial

public static double factorial(int n)

Returns n!, that is, the product of the first n positive integers, 1 if n == 0, or e n!}, or Double.POSITIVE_INFINITY if n! > Double.MAX_VALUE.

The result is within 1 ulp of the true value.

Throws:

IllegalArgumentException - if n < 0