function [thetav,rhov] = cart2cyluv(u,v,thetai,rhoi,varargin)
% z=cart2cyl(c,xi,yi);
%

NN=size(u);
[x y nz]=size(u);
stepx=(x+1)/(x);
stepy=(y+1)/(y);
[Y,X] = meshgrid(-(x)/2:stepx:(x)/2,-(y)/2:stepy:(y)/2);
[theta,rho] = cart2pol(X,Y);


% switches to increasing c-clockwise instead of clockwise
theta=-theta;

%original
%azimv=u.*cos(theta)+v.*-sin(theta);
%radialv=u.*sin(theta)+v.*cos(theta);

% 2nd try
%azimv=u.*cos(theta)+v.*sin(theta);
%radialv=u.*sin(theta)+v.*-cos(theta);

%azimv=u.*-cos(theta); %good
%radialv=u.*-sin(theta);%good 

%azimv=v.*-sin(theta); % good
%radialv=v.*cos(theta); % good

% 3rd's the charm 
azimv=u.*-cos(theta)+v.*-sin(theta);
radialv=u.*-sin(theta)+v.*cos(theta);

theta=(theta./(pi*2)+0.5).*(size(thetai,2));
rho=max(rhoi)*rho/((x)/2);
ntheta=x;nrho=y;

THETA=reshape(theta,[1 ntheta*nrho]);
RHO=reshape(rho,[1 ntheta*nrho]);
del=griddata_preprocess(RHO,THETA,rhoi,thetai',varargin{:});

for k=1:nz;
 THETAV=reshape(azimv(:,:,k),[1 ntheta*nrho]);
 RHOV=reshape(radialv(:,:,k),[1 ntheta*nrho]);
thetav(:,:,k)=griddata(RHO,THETA,THETAV,rhoi,thetai',varargin{:});
rhov(:,:,k)=griddata(RHO,THETA,RHOV,rhoi,thetai',varargin{:});
end % k

% Split vertical and time dimensions
if size(NN,2)>2
thetav=reshape(thetav,[size(thetav,1) size(thetav,2) NN(3:end)]);
rhov=reshape(rhov,[size(rhov,1) size(rhov,2) NN(3:end)]);
end