Error in quiver plot

I am trying to plot velocity vectors of the geostrophic wind I have calculated using geopotential height. The final result is a blank plot for the quiver with lat and lon marked. I am unable to find the error. Kindly help me with the same.

ncdisp("_grib2netcdf-webmars-public-svc-blue-006-6fe5cac1a363ec1525f54343b6cc9fd8-NXI9Ix.nc")
time=ncread("_grib2netcdf-webmars-public-svc-blue-006-6fe5cac1a363ec1525f54343b6cc9fd8-NXI9Ix.nc",'time');
lon=ncread("_grib2netcdf-webmars-public-svc-blue-006-6fe5cac1a363ec1525f54343b6cc9fd8-NXI9Ix.nc",'longitude');
lat=ncread("_grib2netcdf-webmars-public-svc-blue-006-6fe5cac1a363ec1525f54343b6cc9fd8-NXI9Ix.nc",'latitude');
z=ncread("_grib2netcdf-webmars-public-svc-blue-006-6fe5cac1a363ec1525f54343b6cc9fd8-NXI9Ix.nc",'z');
u=ncread("_grib2netcdf-webmars-public-svc-blue-006-6fe5cac1a363ec1525f54343b6cc9fd8-NXI9Ix.nc",'u');
v=ncread("_grib2netcdf-webmars-public-svc-blue-006-6fe5cac1a363ec1525f54343b6cc9fd8-NXI9Ix.nc",'v');

contourf(lon,lat,v(:,:,3)')
contourf(lon,lat(1:50),u(:,1:50,3)')
colorbar

colorbar
phi=lat*pi/180;
size(phi)
x=lon*pi/180;
omega=2*pi/(24*3600);
f=2*omega*sin(phi);

y_diff=abs(lat(1)-lat(2))*111000;
x_diff=111000*abs(lon(1)-lon(2)).*cos(phi);
F=repmat(f,1,480);% changing f to a 2d matrix to ease the multiplication
size(z(:,:,2))
% using central difference scheme to evaluate derivatives
z_y=zeros(480,241);
for i=2:240
    z_y(:,i)=-(z(:,i+1,3)-z(:,i-1,3));
end
z_y=z_y/(2*y_diff);

z_x=zeros(480,241);
for i=2:479
    z_x(i,:)=z(i+1,:,3)-z(i-1,:,3);
end

z_x=z_x./(2*x_diff)';

ug=-z_y./F';
vg=z_x./F';
contourf(lon,lat(1:50),ug(:,1:50)')
colorbar
contourf(lon,lat,vg')
colorbar

contourf(lon,lat,z(:,:,3)')
colorbar
%hold on
[lat, lon]=meshgrid(lat, lon);
quiver(lon,lat,ug,vg);

[VBBV]

[lat, lon]=meshgrid(min(lat):max(lat), min(lon):max(lon));  % use a range for meshgrid 

use a range for lat and lon in meshgrid

[Mehak S]

Output is still not showing anything. No change.

[Voss]

@Mehak S Can you upload those files (using the paperclip button), so that we may reproduce the problem?