Class MathUtil

java.lang.Object
info.monitorenter.util.math.MathUtil

public final class MathUtil extends Object
Static helpers for working with numbers.

Maybe not always the fastest solution to call in here, but working. Also usable for seeing examples and cutting code for manual inlining.

Version:
$Revision: 1.3 $
Author:
Achim.Westermann@gmx.de
  • Method Summary

    Modifier and Type
    Method
    Description
    static void
    assertDouble(double d)
    Asserts that the given double is not invalid for calculation.
    static boolean
    assertEqual(double d1, double d2, double precisionRange)
    Asserts if the given two doubles are equal within the given precision range by the operation:
    static MathUtil
    Returns the singleton instance of this class.
    static Integer
    Raises the given integer by one (bad performance).
    static boolean
    isDouble(double d)
    Tests that the given double is not invalid for calculation.

    Methods inherited from class java.lang.Object

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

    • assertDouble

      public static void assertDouble(double d) throws IllegalArgumentException
      Asserts that the given double is not invalid for calculation.

      It must not be one of:

      Parameters:
      d - the double to test.
      Throws:
      IllegalArgumentException - if the assertion fails.
    • assertEqual

      public static boolean assertEqual(double d1, double d2, double precisionRange)
      Asserts if the given two doubles are equal within the given precision range by the operation:
       Math.abs(d1 - d2) < precision
       
      .

      Because floating point calculations may involve rounding, calculated float and double values may not be accurate. This routine should be used instead. If called with a very small precision range this routine will not be stable against the rounding of calculated floats but at least prevent a bug report of the findbugs tool. See the Java Language Specification, section 4.2.4.

      Parameters:
      d1 - a double to check equality to the other given double.
      d2 - a double to check equality to the other given double.
      precisionRange - the range to allow differences of the two doubles without judging a difference - this is typically a small value below 0.5.
      Returns:
      true if both given doubles are equal within the given precision range.
    • getInstance

      public static MathUtil getInstance()
      Returns the singleton instance of this class.

      This method is useless for now as all methods are static. It may be used in future if VM-global configuration will be put to the state of the instance.

      #

      Returns:
      the singleton instance of this class.
    • increment

      public static Integer increment(Integer value)
      Raises the given integer by one (bad performance).

      Warning: Only use this for testing code or prototypes as a new instance might be created for each call. Use primitive data types when fast calculations are required.

      Warning: Never do the following: Integer count = new Integer(6); MathUtil.increment(count); // don't expect count now carries 6. Integers are immutable. Write: Integer count = new Integer(6); count = MathUtil.increment(count);

      Parameters:
      value - the value to increase, if null is used a new instance will be initialized with value 0 and incremented.
      Returns:
      a (potentially new by the means of Integer.valueOf(int)) value increased by one.
    • isDouble

      public static boolean isDouble(double d)
      Tests that the given double is not invalid for calculation.

      It must not be one of:

      Parameters:
      d - the double to test.
      Returns:
      true if the given double is valid for calculation (not infinite or NaN).