v1v2.pro (Kronos IDL library)

;+
; Contains the v1v2 function
;
; :Author:
;    Baptiste Cecconi
;
; :History:
;    2004/12/03: Created
;
;    2004/12/03: Last Edit
;-
;
;+
; autocorrelation & Re (cross-correlation)
;
; :Returns:
;    <return desc here>
;
; :Params:
;    S:    in, required, type=sometype
;       A parameter named S
;    h1:   in, required, type=sometype
;       A parameter named h1
;    h2:   in, required, type=sometype
;       A parameter named h2
;    al1i: in, required, type=sometype
;       A parameter named al1i
;    al2i: in, required, type=sometype
;       A parameter named al2i
;    be1i: in, required, type=sometype
;       A parameter named be1i
;    be2i: in, required, type=sometype
;       A parameter named be2i
;    Q:    in, required, type=sometype
;       A parameter named Q
;    U:    in, required, type=sometype
;       A parameter named U
;    thi:  in, required, type=sometype
;       A parameter named thi
;    phi:  in, required, type=sometype
;       A parameter named phi
;
; :Keywords:
;    deg:  in, optional, type=sometype
;       A keyword named deg
;-
function V1V2, S,h1,h2,al1i,al2i,be1i,be2i,Q,U,thi,phi,deg=deg

if keyword_set(deg) then begin
    al1 = al1i/!radeg
    al2 = al2i/!radeg
    be1 = be1i/!radeg
    be2 = be2i/!radeg
    th = thi/!radeg
    ph = phi/!radeg
endif else begin
    al1 = al1i
    al2 = al2i
    be1 = be1i
    be2 = be2i
    th = thi
    ph = phi
endelse


V12=0.5*S*h1*h2*( (1.+Q)* (cos(al1)*sin(th)-sin(al1)*cos(th)*cos(ph-be1))* $
                  (cos(al2)*sin(th)-sin(al2)*cos(th)*cos(ph-be2))- $
                  U*sin(al2)*sin(ph-be2)* (cos(al1)*sin(th)-sin(al1)*cos(th)*cos(ph-be1))- $
                  U*sin(al1)*sin(ph-be1)* (cos(al2)*sin(th)-sin(al2)*cos(th)*cos(ph-be2))+ $
                  (1.-Q)* sin(al1)*sin(al2)*sin(ph-be1)*sin(ph-be2) )

 return, V12
end