`arithmetic`

Performs an arithmetical calculation on two numbers (a left-hand-side number and a right-hand-side number) and optionally rounds the result to the specified number of decimal places.

The operations supported are:

Addition
left hand side + right hand side;
Subtraction
left hand side - right hand side;
Multiplication
left hand side * right hand side; and
Division
left hand side / right hand side.

If rounding is required, then you must specify:

the number of decimal places to round to; and
the rounding mode, i.e. the direction in which to round when rounding is performed. See the JavaDoc for RoundingMode for the list of supported rounding modes and a detailed explanation of their behavior.

warning: For division operations, in general you should supply a rounding mode and a number of decimal places. If you do not, and at runtime an exact result cannot be calculated, then a runtime error will occur.

The CER rule set validator will issue a warning if it detects any division operation in your rule set which does not specify rounding specified.

<?xml version="1.0" encoding="UTF-8"?>
<RuleSet name="Example_arithmetic"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:noNamespaceSchemaLocation=
"http://www.curamsoftware.com/CreoleRulesSchema.xsd">
  <Class name="ArithmeticExampleRuleClass">

    <!-- 3 + 2 = 5 -->
    <Attribute name="addANumberToAnother">
      <type>
        <javaclass name="Number"/>
      </type>
      <derivation>
        <arithmetic operation="+">
          <Number value="3"/>
          <Number value="2"/>
        </arithmetic>
      </derivation>
    </Attribute>

    <!-- 3 - 2 = 1 -->
    <Attribute name="subtractANumberFromAnother">
      <type>
        <javaclass name="Number"/>
      </type>
      <derivation>
        <arithmetic operation="-">
          <Number value="3"/>
          <Number value="2"/>
        </arithmetic>
      </derivation>
    </Attribute>

    <!-- 3 * 2 = 6 -->
    <Attribute name="multiplyANumberByAnother">
      <type>
        <javaclass name="Number"/>
      </type>
      <derivation>
        <arithmetic operation="*">
          <Number value="3"/>
          <Number value="2"/>
        </arithmetic>
      </derivation>
    </Attribute>

    <!-- 3 / 2 = 1.5 -->
    <!-- Because the division is by 2,
         we can get away without rounding.
         A warning will still be issued by the
         CER rule set validator, though.   -->
    <Attribute name="divideANumbersByAnother">
      <type>
        <javaclass name="Number"/>
      </type>
      <derivation>
        <arithmetic operation="/">
          <Number value="3"/>
          <Number value="2"/>
        </arithmetic>
      </derivation>
    </Attribute>

    <!-- (3 + 2) * 4 = 20 -->
    <Attribute name="chainedArithmetic">
      <type>
        <javaclass name="Number"/>
      </type>
      <derivation>
        <arithmetic operation="*">
          <arithmetic operation="+">
            <Number value="3"/>
            <Number value="2"/>
          </arithmetic>
          <Number value="4"/>
        </arithmetic>
      </derivation>
    </Attribute>

    <!-- 1.23 + 3.45 = 4.68,
         = 4.7 when rounded to the nearest 1 decimal place-->
    <Attribute name="roundedAddition">
      <type>
        <javaclass name="Number"/>
      </type>
      <derivation>
        <arithmetic decimalPlaces="1" operation="+"
          rounding="half_up">
          <Number value="1.23"/>
          <Number value="3.45"/>
        </arithmetic>
      </derivation>
    </Attribute>

    <!-- 2 / 3, = 0.667 to 3 decimal places -->
    <!-- If no rounding is specified,
         then a runtime error will occur -->
    <Attribute name="roundedDivision">
      <type>
        <javaclass name="Number"/>
      </type>
      <derivation>
        <arithmetic decimalPlaces="3" operation="/"
          rounding="half_up">
          <Number value="2"/>
          <Number value="3"/>
        </arithmetic>
      </derivation>
    </Attribute>

  </Class>

</RuleSet>