q_rot.pro (Kronos IDL library)

;+
; Contains the q_rot function
;
; :Author:
;    Baptiste Cecconi
;
; :History:
;    2005/01/13: Created
;
;    2005/01/13: Last Edit
;-
;
;+
; q_rot is a function that <behavior desc here>
;
; :Uses:
;    q_prod
;
; :Returns:
;    <return desc here>
;
; :Params:
;    qrot: in, required, type=sometype
;       A parameter named qrot
;    qvec: in, required, type=sometype
;       A parameter named qvec
;-
FUNCTION Q_rot,qrot,qvec

sr = size(qrot)
sv = size(qvec)

nr = (sr(0) eq 1) + (sr(0) eq 2)*sr(2)
nv = (sv(0) eq 1) + (sv(0) eq 2)*sv(2)

err = bytarr(3)
err(0) = sr(1) ne 4 or nr eq 0
err(1) = sv(1) ne 4 or nv eq 0
err(2) = not (nr eq 1 or nv eq 1 or (nr eq nv and nr ne 1 and nv ne 1) )
err = err mod 2

if (where(err ne 0))(0) ne -1 then begin
    print,"Q_ROT : error, wrong argument size..."
    print," Use : Q_ROT,qrot,qvec"
    if err(0) then print," > qrot must be a quaternion (4) or a vector of quaternions (4,n)"
    if err(1) then print," > qvec must be a quaternion (4) or a vector of quaternions (4,n)"
    if err(2) then print," > in case of vector of quaternions (4,n1) and (4,n2), n1=n2 is required"
    return,-1
endif

qres = Q_prod(Q_prod(qrot,qvec),Q_conj(Qrot))


return,qres
end