Observer Command
nsum `variable1 variable2` For each patch, takes the sum of `variable1` from all neighboring patches and places it in `variable2`. `Variable` should be a patch variable. Note: `nsum` must be run by the observer, even though it affects patches. Examples: `nsum food surrounding-food` takes the food variable of all the surrounding patches and stores the value of their sum in the patch-variable surrounding-food. Related commands: nsum4 diffuse