Implicit index
An Implicit index (also known as a null-index) is an index that does not have a name, e.g. a list (a 1-dimensional array) with its single dimension not explicitly named.
Because an implicit index has no name, it is not possible to refer to it in expressions where index parameters are expected.
Most built-in Analytica functions can still be employed to operate over implicit indexes, e.g. the Subset function with the optional «position» parameter:
Subset(1997..2008 > 2005, position: true) → [10, 11, 12]-- returns positions of elements
vs
Index Years := 1997..2008Subset(Years > 2005) → [2006, 2007, 2008]-- returns index values
To avoid ambiguity, Analytica does not allow more than one implicit index in an array. If you try to combine multiple arrays with implicit indexes, it will cause an error.
When an implicit index reaches the top level of an expression, it is promoted to a Self index.
Implicit indexes define implicit dimensions, e.g. (-3..3) or [-3, -2, -1, 0, 1, 2, 3]. Indexes that do have a name, are called explicit indexes and define explicit dimensions, e.g. Index I := 1..10.
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