set-scale in dc<%>
Sets a scaling factor that maps logical coordinates to device coordinates.
Changing a dc<%> object's origin or scale invalidates
region% objects associated with the device context. See
region% for more information.
Restrictions on the magnitude of
drawing coordinates are described with dc<%>.
( -> void
send a-dc set-scale x-scale y-scale)
x-scale : non-negative real number
y-scale : non-negative real number