! &1  name of the first  array (x)
! &2  name of the second array (y)
! &3  sign of the rotation
!
define real nonono sign
let found1 exist(nonono&1) /new logi
let found2 exist(nonono&2) /new logi
if (found1.or.found2) then
  say "Usage:  ROTATE Array1 Array2 [Clockwise = 1, CounterClockwise = -1]"
  return
endif 
if (.not.found1.and..not.exist(&1)) then
  say "Undefined array &1"
  return
endif
if (.not.found2.and..not.exist(&2)) then
  say "Undefined array &2"
  return
endif
if (.not.exist(el)) then
  say "No scan (elevation undefined)"
  return
endif
let sign 0&3
if (sign.eq.0) then
  say "... rotating clockwise"
endif
let sign sign+1e-6
let sign nint(abs(sign)|sign)
!
define real du /like &2
define real m cm sm em
define inte n
let du[1] 1
compute m mean du
!
let n nint(1|m)
compute em mean el
let em em|180*pi*sign
let cm cos(em)
let sm sin(em)
let du  &1*cm-&2*sm
let &2  &1*sm+&2*cm
let &1 du