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Introduction for Programmers

Even though the syntax of the Math module has many features similar to a programming language, it is important to keep in mind that the Math module is not a programming language.
It is merely a collection of formulas that is evaluated formula by formula with each iteration of the module. The focus here is on the time relationship between the individual signals. There must never be a situation where a result value is no longer defined at a certain point in time. This is why certain constructs do not work, such as

if (someCondition)
  y = 2 * x;

How should y be determined if the condition is not met?

Accordingly, you may miss some programming language functions - probably the most noticeable is that there are no control flow constructs.

A few examples of functions that can be used to achieve a type of conditional execution can be found here:

Conditional execution​

Ternary Operator ?​

The feature that is probably most similar to classic flow control features is the ternary operator, which works in the Math module in the same way as in common programming languages.

Example​

Valve = temperature > 25.0 ? 20.0 : 80.0;

In programming language​

Valve = Temperature > 25.0 ? 20.0 : 80.0;
// or
if (temperature > 25.0)
   valve = 20.0;
else
   Valve = 80.0;

Controlled switch

warning

When using the ternary operator, care must be taken not to write the following error-prone constructs:

Result = Measured value != 0.0 ? Maximum / measured value : -1.0; This can lead to a division by zero.

Instead: Result = Maximum / nonZero(Measured value);

Select function​

To select a specific value from a set of available values, the select() function can be used.

Example​

Select = select(Index, Value0, Value1, Value2, Value3);

In programming language​

switch(index)
  {
    case 0: selection = value0; break;
    case 1: selection = value1; break;
    case 2: selection = value2; break;
    case 3: selection = value3; break;
    default: selection = false;
  }

Priority encoder​

To select a value based on a set of conditions, the prioEnc() function can be used.

Example​

Status = prioEnc(condition0, condition1, condition2, condition3, {none: 1000, map: [10,20,30,40]});

In programming language​

if (condition0)
  Status = map[0]; // = 10
else if(condition1)
  Status = map[1]; // = 20
else if (condition2)
  Status = map[2]; // = 30
else if (condition3)
  Status = map[3]; // = 40
else
  Status = none; // = 1000

There are also further options here via the parameterization of the function, e.g. detecting edges as a condition or holding and continuing the last set condition if no other is set.

Value range limitation​

The range() function can be used to restrict a measured value to a specific value range.

Limit value range

Example​

Limited = range(measured value, [-10.0, 10.0]);

In programming language​

if (measured value < -10.0)
   Limited = -10.0;
else if (measured value > 10.0)
  Limited = 10.0;
else
  Limited = measured value;

Alternatively, any values can be specified that are to be output if the lower or upper limit is reached.

Example​

Limited = range(measured value, [-10.0, 10.0], {lower: -99, upper: 99});

In programming language​

if (measured value < -10.0)
   Limited = lower; // = -99;
else if (measured value > 10.0)
  Limited = upper; // = 99;
else
  Limited = measured value;

Store values temporarily​

So-called flip-flops can be used to save values between iterations of the Math module.

rsFF​

The rsFF() function can be used to save a Boolean value.

Example​

State = rsFF(ConditionReset, ConditionSet);

In programming language​

if (ConditionReset)
  condition = false;
else if (ConditionSet)
  Condition = true;
else
  State = last state;

dLatch​

The function dLatch() can be used to save a value of any data type.

Example​

flag = dLatch(conditionHold, measured value);

In programming language:​

if (conditionHold)
  flag = last flag;
else
  flag = measured value;