Package com.google.common.math

Class DoubleMath

    • Method Detail

      • roundToInt

        @GwtIncompatible
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

        @GwtIncompatible
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

      • isPowerOfTwo

        @GwtIncompatible
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 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.

      • log2

        @GwtIncompatible
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

        @GwtIncompatible
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 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

      • fuzzyEquals

        public static boolean fuzzyEquals​(double a,
                                  double b,
                                  double tolerance)
        Returns 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:

        • All NaNs are fuzzily equal.
        • If a == b, then a and b are always fuzzily equal.
        • Positive and negative zero are always fuzzily equal.
        • If tolerance is zero, and neither a nor b is NaN, then a and b are fuzzily equal if and only if a == b.
        • With Double.POSITIVE_INFINITY tolerance, all non-NaN values are fuzzily equal.
        • With finite tolerance, 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.

        Throws:
        IllegalArgumentException - if tolerance is < 0 or NaN
        Since:
        13.0

      • fuzzyCompare

        public static int fuzzyCompare​(double a,
                               double b,
                               double tolerance)
        Compares 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.

        Throws:
        IllegalArgumentException - if tolerance is < 0 or NaN
        Since:
        13.0

      • mean

        @Deprecated
public static double mean​(long... values)
        Deprecated.
        Use Stats.meanOf(java.lang.Iterable<? extends java.lang.Number>) instead, noting the less strict handling of non-finite values.
        Returns the arithmetic mean of values.

        If these values are a sample drawn from a population, this is also an unbiased estimator of the arithmetic mean of the population.

        Parameters:
        values - a nonempty series of values, which will be converted to double values (this may cause loss of precision for longs of magnitude over 2^53 (slightly over 9e15))
        Throws:
        IllegalArgumentException - if values is empty