pro two_source_fit,vis,xpos,ypos,SC=sc
;
;PURPOSE:
; Given the source positions for a double source, find the
; relative amplitudes and fluxes from a given subcollimator set 
; sc is set of 3 or more subcollimators from 1 to 9

; METHOD:
;  Uses vis = F1*R1(k)*exp(ik.x1)+F2*R2(k)*exp(ik.x2)


default,sc,[5,6,7]

if n_elements(sc) lt 3 then message,'Fewer than 3 subcollimators'

pitch=(hsi_grid_parameters()).pitch
k=1/pitch
wsc0=where(vis.isc eq sc[0],n0)
wsc1=where(vis.isc eq sc[1],n1)
wsc2=where(vis.isc eq sc[2],n2)
pa0=atan(vis[wsc0].v,vis[wsc0].u)
pa1=atan(vis[wsc1].v,vis[wsc1].u)
pa2=atan(vis[wsc2].v,vis[wsc2].u)

i=complex(0,1)
; for first sc:
kx=k[sc[0]-1]*cos(pa0)
ky=k[sc[0]-1]*sin(pa0)
phz1=kx*xpos[0]+ky*ypos[0]
phz2=kx*xpos[1]+ky*ypos[1]

; find best fit to V = RF1*exp(i*phz1)+RF2*exp(i*phz2)
;    Vreal=a*cos(phz1)+b*cos(phz2) ; for n0 values
;    Vimag=a*sin(phz1)+b*sin(phz2); for n0 values







return
end

restore,'MEMfit_sigvis_phzradset_2003-06-17_225310-225440E30-60ff.sav',/ver