% converts U (rho), V (theta) and W in polar coords into 
% proper u,v, and w in cartesian coords, plus into theta and
% rho vector components in a more physical annulus layout

if (1) 
% load data
Wwhole=rdmds('W');
%Twhole=rdmds('T');
W=Wwhole(:,:,15);
% set null-space areas to NaN (makes interpolation happier)
W(find(W==0))=NaN;
%T(find(T==0))=NaN;
%W(120,:)=0.005;
[ydim xdim]=size(W);
else
xdim=31;
ydim=120;
[X Y ]=meshgrid(1:xdim,1:ydim);
W=X;
W(:,1:8)=nan;
W(:,31)=nan;
%W(:,9)=26;


end



% this determines resolution of interpolated fields
% 0.5 is perhaps a bit fine, but it looks pretty
%step=0.5;
% good for quiver plots
% step=1;
step=(xdim*2+1)/(xdim*2);


rhoi=1:31;
thetai=1:120;
z=1;




% convert w (effectively a scalar)
 w=cyl2cart(W,-xdim:step:xdim,-xdim:step:xdim);
 Wback=cart2cyl(w,thetai,rhoi);
% Tc=cyl2cart(T,-30:step:30,-30:step:30);
figure(1);imagesc(W(:,:,z));colorbar;
figure(2);imagesc(w(:,:,z));colorbar;
figure(3);imagesc(Wback(:,:,z));colorbar;
Werr=Wback-W;
figure(4);imagesc(Werr(:,:,z));colorbar;