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Since stable build 2013.02 it is also possible to use the calculated output value of the previous time step, by using "PREVIOUS_OUTPUT_VALUE" in uppercase letters in the expression (can be used multiple times). For each calculation time step "PREVIOUS_OUTPUT_VALUE" is replaced with the previous output value from the output time series. For the first calculation time step in the run period, the previous output value from before the start of the run period is read from the existing output time series in the database (e.g. from a previous run), if present. If for a given calculation time step the previous output value is not present or is unreliable, then "PREVIOUS_OUTPUT_VALUE" is replaced with NaN (missing value).
To write a missing value (NaN) the expression "1/0" can be used.
Furthermore it is possible to use "if statements" in the expression. This can e.g. be used to get one output value if X is greater than 3 and get another output value if X is equal to or less than 3. For instance in the expression
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When using coefficient set functions (available since build 30246), the value elements can contain tags between "@" signs (e.g. "@NUMBER@") that refer to location attributes that are defined in the locationSets configuration file. The tags are replaced by actual values. These values can be different for different locations and time periods. See 22 Locations and attributes defined in CSV files, Shape-DBF files or external tables for more information.
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