Here, you will clearly see the number of arguments required and expected:
Dual - script and chart function
Dual() combines a number and a string into a single record, such that the number representation of the record can be used for sorting and calculation purposes, while the string value can be used for display purposes
Return data type: dual
The string value to be used in combination with the number argument.
The number to be used in combination with the string in the string argument.
In QlikView, all field values are potentially dual values. This means that the field values can have both a numeric value and a textual value. An example is a date that could have a numeric value of 40908 and the textual representation ‘2011-12-31’.
When several data items read into one field have different string representations but the same valid number representation, they will all share the first string representation encountered.
The dual function is typically used early in the script, before other data is read into the field concerned, in order to create that first string representation, which will be shown in list boxes.