Class Arithmetic


  • public class Arithmetic
    extends java.lang.Object
    Standard arithmetic functions including things like rounding, sign manipulation, and maximum/minimum functions. Phase folding operations, and a convenient form of the modulus operation on which they are based, are also provided.
    Since:
    2 Sep 2004
    Author:
    Mark Taylor (Starlink)
    • Method Summary

      All Methods Static Methods Concrete Methods 
      Modifier and Type Method Description
      static double abs​(double x)
      Returns the absolute value of a floating point value.
      static int abs​(int x)
      Returns the absolute value of an integer value.
      static int max​(int a, int b)
      Returns the greater of two integer values.
      static double maxNaN​(double a, double b)
      Returns the greater of two floating point values.
      static double maxReal​(double a, double b)
      Returns the greater of two floating point values, ignoring blanks.
      static int min​(int a, int b)
      Returns the smaller of two integer values.
      static double minNaN​(double a, double b)
      Returns the smaller of two floating point values.
      static double minReal​(double a, double b)
      Returns the smaller of two floating point values, ignoring blanks.
      static double mod​(double a, double b)
      Returns the non-negative remainder of a/b.
      static double phase​(double t, double period)
      Returns the phase of a value within a period.
      static double phase​(double t, double period, double t0)
      Returns the phase of an offset value within a period.
      static double phase​(double t, double period, double t0, double phase0)
      Returns the offset phase of an offset value within a period.
      static int round​(double x)
      Rounds a value to the nearest integer.
      static float roundDecimal​(double x, int dp)
      Rounds a value to a given number of decimal places.
      static int roundDown​(double x)
      Rounds a value down to an integer value.
      static int roundUp​(double x)
      Rounds a value up to an integer value.
      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
    • Method Detail

      • roundUp

        public static int roundUp​(double x)
        Rounds a value up to an integer value. Formally, returns the smallest (closest to negative infinity) integer value that is not less than the argument.
        Parameters:
        x - a value.
        Returns:
        x rounded up
      • roundDown

        public static int roundDown​(double x)
        Rounds a value down to an integer value. Formally, returns the largest (closest to positive infinity) integer value that is not greater than the argument.
        Parameters:
        x - a value
        Returns:
        x rounded down
      • round

        public static int round​(double x)
        Rounds a value to the nearest integer. Formally, returns the integer that is closest in value to the argument. If two integers are equally close, the result is the even one.
        Parameters:
        x - a floating point value.
        Returns:
        x rounded to the nearest integer
      • roundDecimal

        public static float roundDecimal​(double x,
                                         int dp)
        Rounds a value to a given number of decimal places. The result is a float (32-bit floating point value), so this is only suitable for relatively low-precision values. It's intended for truncating the number of apparent significant figures represented by a value which you know has been obtained by combining other values of limited precision. For more control, see the functions in the Formats class.
        Parameters:
        x - a floating point value
        dp - number of decimal places (digits after the decimal point) to retain
        Returns:
        floating point value close to x but with a limited apparent precision
        Examples:
        roundDecimal(PI,2) = 3.14f
      • abs

        public static int abs​(int x)
        Returns the absolute value of an integer value. If the argument is not negative, the argument is returned. If the argument is negative, the negation of the argument is returned.
        Parameters:
        x - the argument whose absolute value is to be determined
        Returns:
        the absolute value of the argument.
      • abs

        public static double abs​(double x)
        Returns the absolute value of a floating point value. If the argument is not negative, the argument is returned. If the argument is negative, the negation of the argument is returned.
        Parameters:
        x - the argument whose absolute value is to be determined
        Returns:
        the absolute value of the argument.
      • max

        public static int max​(int a,
                              int b)
        Returns the greater of two integer values. If the arguments have the same value, the result is that same value.

        Multiple-argument maximum functions are also provided in the Arrays and Lists packages.

        Parameters:
        a - an argument.
        b - another argument.
        Returns:
        the larger of a and b.
      • maxNaN

        public static double maxNaN​(double a,
                                    double b)
        Returns the greater of two floating point values. If the arguments have the same value, the result is that same value. If either value is blank, then the result is blank.
        Parameters:
        a - an argument.
        b - another argument.
        Returns:
        the larger of a and b.
      • maxReal

        public static double maxReal​(double a,
                                     double b)
        Returns the greater of two floating point values, ignoring blanks. If the arguments have the same value, the result is that same value. If one argument is blank, the result is the other one. If both arguments are blank, the result is blank.

        Multiple-argument maximum functions are also provided in the Arrays and Lists packages.

        Parameters:
        a - an argument
        b - another argument
        Returns:
        the larger non-blank value of a and b
      • min

        public static int min​(int a,
                              int b)
        Returns the smaller of two integer values. If the arguments have the same value, the result is that same value.

        Multiple-argument minimum functions are also provided in the Arrays and Lists packages.

        Parameters:
        a - an argument.
        b - another argument.
        Returns:
        the smaller of a and b.
      • minNaN

        public static double minNaN​(double a,
                                    double b)
        Returns the smaller of two floating point values. If the arguments have the same value, the result is that same value. If either value is blank, then the result is blank.
        Parameters:
        a - an argument.
        b - another argument.
        Returns:
        the smaller of a and b.
      • minReal

        public static double minReal​(double a,
                                     double b)
        Returns the smaller of two floating point values, ignoring blanks. If the arguments have the same value, the result is that same value. If one argument is blank, the result is the other one. If both arguments are blank, the result is blank.

        Multiple-argument minimum functions are also provided in the Arrays and Lists packages.

        Parameters:
        a - an argument
        b - another argument
        Returns:
        the larger non-blank value of a and b
      • mod

        public static double mod​(double a,
                                 double b)
        Returns the non-negative remainder of a/b. This is a modulo operation, but differs from the expression a%b in that the answer is always >=0 (as long as b is not zero).
        Parameters:
        a - dividend
        b - divisor
        Returns:
        non-negative remainder when dividing a by b
        Examples:
        modulo(14, 5) = 4, modulo(-14, 5) = 1, modulo(2.75, 0.5) = 0.25
      • phase

        public static double phase​(double t,
                                   double period)
        Returns the phase of a value within a period.

        For positive period, the returned value is in the range [0,1).

        Parameters:
        t - value
        period - folding period
        Returns:
        mod(t,period)/period
        Examples:
        phase(7, 4) = 0.75, phase(-1000.5, 2.5) = 0.8, phase(-3300, 33) = 0
      • phase

        public static double phase​(double t,
                                   double period,
                                   double t0)
        Returns the phase of an offset value within a period. The reference value t0 corresponds to phase zero.

        For positive period, the returned value is in the range [0,1).

        Parameters:
        t - value
        period - folding period
        t0 - reference value, corresponding to phase zero
        Returns:
        phase(t-t0, period)
        Examples:
        phase(5003,100,0) = 0.03, phase(5003,100,2) = 0.01, phase(5003,100,4) = 0.99
      • phase

        public static double phase​(double t,
                                   double period,
                                   double t0,
                                   double phase0)
        Returns the offset phase of an offset value within a period. The reference value t0 corresponds to integer phase value, and the phase offset phase0 determines the starting value for the phase range.

        For positive period, the returned value is in the range [phase0,phase0+1).

        Parameters:
        t - value
        period - folding period
        t0 - reference value, corresponding to phase zero
        phase0 - offset for phase
        Returns:
        offset phase
        Examples:
        phase(23,10,1,99) = 99.2, phase(8.6125,0.2,0.0125,-0.3) = 0, phase(8.6125,0.2,0.1125,-0.7) = -0.5