--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/switchbeams.m	Tue Oct 20 16:23:49 2009 -0400
@@ -0,0 +1,81 @@
+function  [d,p]=switchbeams(d,p)
+% function  [d,p]=switchbeams(d,p)
+% 
+% simple routine to "correct" if beams are switched
+% it only performs this in 2D which is only roughly correct
+% 
+% p.beam_switch=[ 1 1 1]  switch u and v beam pairs down looker
+% p.beam_switch=[ 1 0 2]  switch u not v beam pairs up looker
+% 
+%
+disp('SWITCHBEAMS: ******** switch beams ***********')
+if existf(p,'beam_switch')==0
+ disp(' need to give switch matix p.beam_switch ')
+ return
+end
+
+% first rotate to instrument coordinates
+%
+% heading of beam 3 is
+  hrot = p.drot + d.hdg(p.beam_switch(3),:);
+
+% check if called before
+if existf(d,'ru_orig')==0
+  d.ru_orig=d.ru;
+  d.rv_orig=d.rv;
+  d.bvel_orig=d.bvel;
+else
+  disp(' found ru_orig, will use those to rotate from ')
+end
+
+if p.beam_switch(3)==1
+ iz=d.izd;
+elseif  p.beam_switch(3)==2
+ iz=d.izu;
+else
+ disp(' which instrument shall I switch? ')
+ return
+end
+
+% backrotate to instrument coordinates
+[rui,rvi]=uvrot(d.ru_orig(iz,:),d.rv_orig(iz,:),repmat(-hrot,[length(iz),1]));
+if p.beam_switch(3)==1
+ [bui,bvi]=uvrot(d.bvel_orig(:,1),d.bvel_orig(:,2),-hrot');
+end
+
+
+% switch beams
+if p.beam_switch(1)
+ rui=-rui;
+ bui=-bui;
+ warn=(' switched u-beam pair in instrument coordinates');
+ disp(warn)
+ p.warnp(size(p.warnp,1)+1,1:length(warn))=warn;
+end
+
+if p.beam_switch(2)
+ rvi=-rvi;
+ bvi=-bvi;
+ warn=(' switched v-beam pair in instrument coordinates');
+ disp(warn)
+ p.warnp(size(p.warnp,1)+1,1:length(warn))=warn;
+end
+
+% rotate to earth coordinates
+[ru,rv]=uvrot(rui,rvi,repmat(hrot,[length(iz),1]));
+[bu,bv]=uvrot(bui,bvi,hrot');
+
+d.ru(iz,:)=ru;
+d.rv(iz,:)=rv;
+if p.beam_switch(3)==1
+ d.bvel(:,1)=bu;
+ d.bvel(:,2)=bv;
+end
+
+
+return
+
+
+
+  
+