VECTOR command

Syntax: | `VECTOR v1 { v2 ... } n`

This command defines `v1` to be a vector of length `n`, where `n > 0` must be a scalar value. Other variable names, `v2 ...`, may be included, and they will also be defined to be vectors with the same length.

If `vI` already is a vector, it will either be trimmed down to the specified length or zero filled to expand it.

If `vI` is an existing variable, but not a vector, it will be destroyed first.

If `vI` does not exist, it will be created and zero filled.