utils/cs_grid/rotate_csAg_EN.m

function [uE,vN] = rotate_csAg_EN(u,v)
% [uE,vN] = rotate_csAg_EN(u,v)
%
% Rotate U,V vector components of cs-grid (A-grid) to East,North directions
%  u,v   is a 2-D or 3-D horizontal components of a flow fields.
%  uE,vN are the Eastward,Northward components of the rotated flow field
% assume that the 1rst 2 dimensions of (u,v) are [6*nc nc] for a CS(nc x nc) grid
%
% $Header:  $

%Rac='/home/jmc/grid_cs32/' ;
Rac='grid_files/';

NN=size(u);
[nnx nc nz]=size(u); 
nPg=nnx*nc;
if nnx ~= 6*nc,
 fprintf('Error in CS-dim: %i %i %i \n',NN);
 return
end

u=reshape(u,[nPg nz]);
v=reshape(v,[nPg nz]);

%- rotate toward E,N (lon,lat) directions :
% load COS & SIN of rotation angle:
namfil=['proj_cs',int2str(nc),'_2uEvN.bin'];
fid=fopen([Rac,namfil],'r','b'); uvEN=fread(fid,nPg*2,'real*8'); fclose(fid);
uvEN=reshape(uvEN,[nPg 2]);

uE=zeros(nPg,nz); vN=zeros(nPg,nz);
for k=1:nz;
 uE(:,k)=uvEN(:,1).*u(:,k)-uvEN(:,2).*v(:,k);
 vN(:,k)=uvEN(:,2).*u(:,k)+uvEN(:,1).*v(:,k);
end

uE=reshape(uE,[nnx NN(2:end)]);
vN=reshape(vN,[nnx NN(2:end)]);

return
1	function [uE,vN] = rotate_csAg_EN(u,v)
2	% [uE,vN] = rotate_csAg_EN(u,v)
3	%
4	% Rotate U,V vector components of cs-grid (A-grid) to East,North directions
5	% u,v is a 2-D or 3-D horizontal components of a flow fields.
6	% uE,vN are the Eastward,Northward components of the rotated flow field
7	% assume that the 1rst 2 dimensions of (u,v) are [6*nc nc] for a CS(nc x nc) grid
8	%
9	% $Header: $
10
11	%Rac='/home/jmc/grid_cs32/' ;
12	Rac='grid_files/';
13
14	NN=size(u);
15	[nnx nc nz]=size(u);
16	nPg=nnx*nc;
17	if nnx ~= 6*nc,
18	fprintf('Error in CS-dim: %i %i %i \n',NN);
19	return
20	end
21
22	u=reshape(u,[nPg nz]);
23	v=reshape(v,[nPg nz]);
24
25	%- rotate toward E,N (lon,lat) directions :
26	% load COS & SIN of rotation angle:
27	namfil=['proj_cs',int2str(nc),'_2uEvN.bin'];
28	fid=fopen([Rac,namfil],'r','b'); uvEN=fread(fid,nPg2,'real8'); fclose(fid);
29	uvEN=reshape(uvEN,[nPg 2]);
30
31	uE=zeros(nPg,nz); vN=zeros(nPg,nz);
32	for k=1:nz;
33	uE(:,k)=uvEN(:,1).u(:,k)-uvEN(:,2).v(:,k);
34	vN(:,k)=uvEN(:,2).u(:,k)+uvEN(:,1).v(:,k);
35	end
36
37	uE=reshape(uE,[nnx NN(2:end)]);
38	vN=reshape(vN,[nnx NN(2:end)]);
39
40	return