Arithmetical expression in the C programming language.

 Optional programmable arithmetical expression in the C
 programming language. The expression is edited by means
 of the Attribute Editor at the object's Expression
 attribute. The expression, which does not include '=' ,
 is translated at the compilation.
 The Expression attribute is shown in the object.

 Up to 8 analog ( A1, ..., A8) and 8 digital ( d1, ...,d8)
 inputs.
 Digital inputs may be inverted either by means of the
 Attribute Editor, or by the logical operator '!' in the
 Expression attribute.

 Note! If an arithmetical operator is followed by a graph
 name, e.g. A1, the operator and the graph name have to
 be separated by a space or a left parenthesis.

 If an input is used as a constant quantity it is
 suitable to make the input invisible by marking Unused.
 We prefer to write the constant direct into the Expression
 if it is not supposed to be changed. In this case no
 input is used. On the other hand, if we have to adjust
 the constant in run time it is a good idea to make use
 of an Av or Dv object, as this will make it easier to
 get access to the constant from the object display.
 Unused inputs give compilation errors.
 Mathematical functions in the C programming language
 can be used, for instance:

 - exp(A1)       exponential function
 - log10(A1)     base-10 logarithm of A1
 - sin(A1)       sine of A1
 - (1.2E3 + A1) * ( A2 + 3.7 )   arithmetic, note the constants.
 - fabs( A1)     absolute value
 - pow(A1, A2)   A1 rasied to the A2-th power.
 - there is an often used conditional operator, '?', in
   the C programming language used to evaluate
   alternatives. In the following example '&&' means
   logical AND,
   (d1 && d2) ? A1 + A2 : A3, means that VAL = A1+ A2,
   if d1 and d2 are TRUE , otherwise VAL = A3

 This example shows how digital signals can be counted. Some signals
 are counted if they are TRUE others if they are FALSE and then the
 sum is stored. Note that Di3 is included in the sum if it is FALSE.

• DArithm
• CArithm

 Analog quantity that can be included in the
 Expression attribute. If A1 is
 connected, the external signal is used, otherwise the
 internal attribute AIn1. Changes in AIn1, ..., AIn8 in
 the run time system are taken into consideration.

 Analog quantity that can be included in the
 Expression attribute. If A2 is
 connected, the external signal is used, otherwise the
 internal attribute AIn2. Changes in AIn1, ..., AIn8 in
 the run time system are taken into consideration.

 Analog quantity that can be included in the
 Expression attribute. If A3 is
 connected, the external signal is used, otherwise the
 internal attribute AIn3. Changes in AIn1, ..., AIn8 in
 the run time system are taken into consideration.

 Analog quantity that can be included in the
 Expression attribute. If A4 is
 connected, the external signal is used, otherwise the
 internal attribute AIn4. Changes in AIn1, ..., AIn8 in
 the run time system are taken into consideration.

 Analog quantity that can be included in the
 Expression attribute. If A5 is
 connected, the external signal is used, otherwise the
 internal attribute AIn5. Changes in AIn1, ..., AIn8 in
 the run time system are taken into consideration.

 Analog quantity that can be included in the
 Expression attribute. If A6 is
 connected, the external signal is used, otherwise the
 internal attribute AIn6. Changes in AIn1, ..., AIn8 in
 the run time system are taken into consideration.

 Analog quantity that can be included in the
 Expression attribute. If A7 is
 connected, the external signal is used, otherwise the
 internal attribute AIn7. Changes in AIn1, ..., AIn8 in
 the run time system are taken into consideration.

 Analog quantity that can be included in the
 Expression attribute. If A8 is
 connected, the external signal is used, otherwise the
 internal attribute AIn8. Changes in AIn1, ..., AIn8 in
 the run time system are taken into consideration.

 Digital quantity that can be included in the
 Expression attribute. If d1 is
 connected, the external signal is used, otherwise the
 internal attribute DIn1. Changes in DIn1, ..., DIn8 in
 the run time system are taken into consideration.

 Digital quantity that can be included in the
 Expression attribute. If d2 is
 connected, the external signal is used, otherwise the
 internal attribute DIn2. Changes in DIn1, ..., DIn8 in
 the run time system are taken into consideration.

 Digital quantity that can be included in the
 Expression attribute. If d3 is
 connected, the external signal is used, otherwise the
 internal attribute DIn3. Changes in DIn1, ..., DIn8 in
 the run time system are taken into consideration.

 Digital quantity that can be included in the
 Expression attribute. If d4 is
 connected, the external signal is used, otherwise the
 internal attribute DIn4. Changes in DIn1, ..., DIn8 in
 the run time system are taken into consideration.

 Digital quantity that can be included in the
 Expression attribute. If d5 is
 connected, the external signal is used, otherwise the
 internal attribute DIn5. Changes in DIn1, ..., DIn8 in
 the run time system are taken into consideration.

 Digital quantity that can be included in the
 Expression attribute. If d6 is
 connected, the external signal is used, otherwise the
 internal attribute DIn6. Changes in DIn1, ..., DIn8 in
 the run time system are taken into consideration.

 Digital quantity that can be included in the
 Expression attribute. If d7 is
 connected, the external signal is used, otherwise the
 internal attribute DIn7. Changes in DIn1, ..., DIn8 in
 the run time system are taken into consideration.

 Digital quantity that can be included in the
 Expression attribute. If d8 is
 connected, the external signal is used, otherwise the
 internal attribute DIn8. Changes in DIn1, ..., DIn8 in
 the run time system are taken into consideration.

 The result of the latest Expression evaluation.

 Arithmetic expression in the C programming language.
 The expression is edited by means of the Attribute
 Editor and cannot be changed in the target environment.