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java.lang.Objectcom.google.common.math.DoubleMath
@Beta public final class DoubleMath
A class for arithmetic on doubles that is not covered by Math.
| 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 int |
fuzzyCompare(double a,
double b,
double tolerance)
Compares a and b "fuzzily," with a tolerance for nearly-equal values. |
static boolean |
fuzzyEquals(double a,
double b,
double tolerance)
Returns true if a and b are within tolerance of each other. |
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 |
|---|
public static int roundToInt(double x,
RoundingMode mode)
int value that is equal to x rounded with the specified rounding
mode, if possible.
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
public static long roundToLong(double x,
RoundingMode mode)
long value that is equal to x rounded with the specified rounding
mode, if possible.
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
public static BigInteger roundToBigInteger(double x,
RoundingMode mode)
BigInteger value that is equal to x rounded with the specified
rounding mode, if possible.
ArithmeticException - if
x is infinite or NaN
x is not a mathematical integer and mode is
RoundingMode.UNNECESSARY
public static boolean isPowerOfTwo(double x)
true if x is exactly equal to 2^k for some finite integer
k.
public static double log2(double x)
Special cases:
x is NaN or less than zero, the result is NaN.
x is positive infinity, the result is positive infinity.
x is positive or negative zero, the result is negative infinity.
The computed result is 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.
public static int log2(double x,
RoundingMode mode)
int.
Regardless of the rounding mode, this is faster than (int) log2(x).
IllegalArgumentException - if x <= 0.0, x is NaN, or x is
infinitepublic static boolean isMathematicalInteger(double x)
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).
public static double factorial(int n)
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.
IllegalArgumentException - if n < 0
@Beta
public static boolean fuzzyEquals(double a,
double b,
double tolerance)
true if a and b are within tolerance of each other.
Technically speaking, this is equivalent to
Math.abs(a - b) <= tolerance || Double.valueOf(a).equals(Double.valueOf(b)).
Notable special cases include:
a == b, then a and b are always fuzzily equal.
tolerance is zero, and neither a nor b is NaN, then
a and b are fuzzily equal if and only if a == b.
Double.POSITIVE_INFINITY tolerance, all non-NaN values are fuzzily equal.
Double.POSITIVE_INFINITY and Double.NEGATIVE_INFINITY are fuzzily equal only to themselves.
This is reflexive and symmetric, but not transitive, so it is not an
equivalence relation and not suitable for use in Object.equals(java.lang.Object)
implementations.
IllegalArgumentException - if tolerance is < 0 or NaN
@Beta
public static int fuzzyCompare(double a,
double b,
double tolerance)
a and b "fuzzily," with a tolerance for nearly-equal values.
This method is equivalent to
fuzzyEquals(a, b, tolerance) ? 0 : Double.compare(a, b). In particular, like
Double.compare(double, double), it treats all NaN values as equal and greater than all
other values (including Double.POSITIVE_INFINITY).
This is not a total ordering and is not suitable for use in
Comparable.compareTo(T) implementations. In particular, it is not transitive.
IllegalArgumentException - if tolerance is < 0 or NaN
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