How can I create pcolor map from 2D matrix?

I would like to create pcolor lambertian map with map_m package. I have coordinate data

lon=[-40.375:0.25:75.375];lat=[25.375:0.25:75.375];

The number of longitude and latitude data are 464, 201, respectively. The the data in matrix is stored longitude x latitude:clim(464x201). According to my best knowledge the longitude and latitude have to be same length if I use pcolor(lon,lat,clim). I fixed it by:

[lon, lat]= meshgrid(lon,lat);
lon=lon(:);
lat=lat(:);

After that both lon and lat size is n = 93264. But I do not know how I can create n x n martice from clim? Or how I should use pcolor to plot my clim matrix on lon x lat surface? Thank you for your help in advance!