swap

objarray swap <obj> <index_i> <index_j>

To swap the values pointed by <index_i> and <index_j>

e.g.

set obj [objarray new floatarray -values {1.0 2.0 3.0 4.0} ]
# -> 1.0 2.0 3.0 4.0
objarray swap $obj 1 2
# -> 1.0 3.0 2.0 4.0