Class Arithmetic

java.lang.Object
uk.ac.starlink.ttools.func.Arithmetic

public class Arithmetic extends 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

    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 Details

    • 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