# User Portlet Robert Nachbar
Discussions
Nice live-stream today!
Your points about the susceptible population size are well taken. Unlike modeling chemical reactions in a beaker (the math is the same), one cannot assume instantaneous and uniform mixing in epidemiological models. The population size does have an...
I have not used the NGM method myself, but will need to soon for my own research. I came across this reference recently: Diekmann O, Heesterbeek JA, Roberts MG. The construction of next-generation matrices for compartmental epidemic models. J R...
Maybe there are 2.5 of us! I do a lot of epidemiology modeling, and that is very similar to ecological population modeling. Think Lotka-Voltera preditor-prey models on steroids. :-) I'd like to see what could be done in that area with the systems of...
Rohit's solution gives a Root object, which may not be desirable. To do the selection after the fact, use In:= soln = Solve[a t^3 == b, t] Out= {{t -> b^(1/3)/a^( 1/3)}, {t -> -(((-1)^(1/3)...
The width of columns and height of rows in Grid (and related functions) is controlled by the ItemSize option. The units for width are ems (roughly the width of the m character in the font used) and the units for height are rows. See...
WriteLine write each argument after the first on a new line in the file: WriteLine[file, "Some text that is a question like Solve", RandomChoice[{1, 2, 3, 4, 5}], "+", RandomChoice[{1, 2, 3, 4, 5}]] FilePrint["testQuestion.txt"] ...
Use RuleDelayed instead of Rule: In:= 2 CI[{{2,2}}]+2 CI[{{1,2},{2,1}}]/.CI[l_]:>j^(Total[l][]) Out= 2 j^2+2 j^3
such as Deerwester et al.'s latent semantic indexing? I did some work with that method in the late 1990's.
A user-supplied objective function for NMinimize or FindMinimum needs to be "protected" from premature evaluation when given symbolic input. Therefore, use a definition like this radpatt[x1_?NumberQ] := (Print[x1]; x1 )