Query data is in MESHGRID format, NDGRID format will yield better performance

I would like to take double integral from descrete data (I don't want to use trapz) with integral2.

I did the following code but i get warning that:Query data is in MESHGRID format, NDGRID format will yield better performance.

It suggested to transpose like np=np' and nt=nt' but i get the warning again. Since it is in a for loop, this warning itself slows down my run a lot. what is wrong with my approach? I used all alternatives with phi, phi' ....

also i tried pagetranspose function but did not work...

Appreciate to tell me what is fastest approach if i want to integrate my data with Integral2, where theta, phi and p is given.

theta = linspace(0,pi,nTheta);
phi = linspace(0,2*pi,nPhi);
p=zeros(nPhi,nTheta);
[np,nt]=ndgrid(phi,theta);
f1 = griddedInterpolant(np,nt,p);
f2= @(np,nt) f1(np,nt);

integral2(f2,0,2*pi,0,pi)

[Rik]

If it is the warning itself that slows down the process, you can turn it off (have a look at lastwarn to determine the warning ID).