How can I mathematically show the similarity between these 3 plots? I have 3 3D plots of field strength measured around an antenna.



I want to calculate the mathematical similarity between the points of the field patterns. How can I do this?
thanks

There is more than one way to measure similarity.  Here are three.  They all start with $f(x,y)=|a(x,y)-b(x,y)|$, the function that measures the distance between plot $a$ and plot $b$, at every point.
Method 1: Take the maximum of $f(x,y)$ over the region.  
Method 2: Take the integral of $f(x,y)$ over the region, i.e. the area underneath the surface.
Method 3: Take the integral of $f(x,y)^2$ over the region, and take the square root of the answer.
These are called $L^p$ norms, specifically the $\infty$, $1$ and $2$ norms respectively.  
