The Fill command sets entries of the input Matrix, Vector, or Array A to the specified value val. The value must be of the same type as the input Matrix, Vector, or Array, or an error results. In addition, the input Matrix, Vector, or Array must have rectangular (dense) storage.

The additional parameters, num, offset, and skip, extend Fill command usage. For example, you can set every second element in a Vector, a specific row or column in a Matrix, all entries [4,*,*] in a C_order Array.

The use of these additional parameters is a programmer level feature, and requires detailed knowledge of the storage structure of multi-dimensional rtables under different data orderings (C_order and Fortran_order). For a description of storage under these orderings,  see Fortran_order.

Knowledge of these storage schemes becomes required when you want to compute the num, offset, and skip values to fill a row or column of a Matrix using the Fill command.

Filling the third column of a 6 x 10 C_order Matrix corresponds to acting on the elements  for i from 1 to 6.

- num is the number of elements to fill, which is 6

- offset is the offset of the first element to be filled, which is (3-1)=2

- skip is the distance between consecutive elements (the multiplier of the 'i' above), which is 10.

The resulting command is Fill(6,val,A,2,10).

In contrast, the same operation for a 6 x 10 Fortran_order Matrix corresponds to acting on the elements  for i from 1 to 6. In this case the command is Fill(6,val,A,12,1), which can be abbreviated to Fill(6,val,A,12). This is shown in the following examples.

The default values of the optional parameters are described as follows.

- offset is 0 (start at the very beginning)

- skip is 1 (fill all consecutive elements)

- num is chosen so that the operation does not exceed the storage of the rtable

This function is part of the ArrayTools package, so it can be used in the short form Fill(..) only after executing the command with(ArrayTools).  However, it can always be accessed through the long form of the command by using ArrayTools[Fill](..).