Math Formula (Variable)

This node is superseded by the "Variable Expression" node. We advise to use the "Variable Expression" node instead of this node.

This node evaluates a (free-form) mathematical expression based on the values of the flow variables. The computed results can be either appended as new variable or be used to replace an input variable. Commonly used functions are shown in the list "Mathematical Functions". There are also some constants available, such as pi (the ratio of the circumference of a circle to its diameter) and e (the base of the natural logarithms).

This node uses JEP , the Java Math Expression Parser .

You can reference the integer flow variables like this: $${IflowVar}$$ , the floating point flow variables like this: $${DflowVar}$$ .

NaN values act as value true in boolean expressions and compared to anything (including NaN) in any way (including ==, but not !=, which is like !(... == ...)) is false (0).

Please note the expressions are case sensitive.

Input ports

1. Type: Flow Variable
   Input Variables
   (Optional) input variables

Output ports

1. Type: Flow Variable
   Output variables
   Input variables with the new or replaced output variable.

External resources

• KNIME E-Learning Course: Creation and usage of Flow Variables in a KNIME workflow