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Miscellaneous functions

bool ISDEFINED(anytype)
Return false if the value in the current row is undefined. Is useful to test if a cell in a column with variable shaped arrays contains an array. It can also be used to test if a field in a record is defined.

double NELEMENTS(anytype), double COUNT(anytype)
Return number of elements in an array (1 for a scalar).

double NDIM(anytype)
Return dimensionality of an array (0 for a scalar).

doublearray SHAPE(anytype)
Return shape of an array (returns an empty array for a scalar).

double ROWNUMBER()
Return the row number being tested (first row is row number 0 or 1 depending on the style used).
In combination with function RAND it can, for instance, be used to select arbitrary rows from a table.

double ROWID()
Return the row number in the original table. This is especially useful for returning the result of a selection of a subtable of an AIPS++ measurement set (see also sections Subqueries and Examples).

double RAND()
Return (per table row) a uniformly distributed random number between 0 and 1 using a Multiplicative Linear Congruential Generator. The seeds for the generator are deduced from the current date and time, so the results are different from run to run.
The function can, for instance, be used to select a random subset from a table.

anytype IIF(cond,arg1,arg2)
This is a special funtion which operates like the ternary ?: operator in C++. If all arguments are scalars, the result is a scalar, otherwise an array. In the latter case possible scalar arguments are virtually expanded to arrays. IIF evaluates the condition for each element. If True, it takes the corresponding element of arg1, otherwise of arg2.

anytypearray ARRAY(anytype,shape)
This function creates an array of the given type and shape. The shape is given in the last argument(s). It can be given in two ways:
- As a single set argument; for example, array(0,[3,4])
- As individual scalar arguments; for example, array(0,3,4)
The first argument gives the values the array is filled with. It can be a scalar or an array of any shape. To initialize the created array, the value array is flattened to a 1D array. Its successive values are stored in the created array. If the new array has more values than the value array, the value array is reset to its beginning and the process continues.