Permutations

[Hugo Hernández]

Hello:

I´m trying to simulate a Poisson distribution, but I´m facing the problem of not having the factorial function. I’m running out of ideas. Is there a way in which I can calculate n! or at least the (n, r) permutaion?

[Dan Damelin]

Well, this is not ideal, but if your range for n is limited enough, you could create one table that calculates the various values for n, and then use that table as a lookup for your own n! function. (The lookup table could be closed, so it would not be visible.)

See example here:

https://codap.concord.org/releases/latest/static/dg/en/cert/index.html#shared=https%3A%2F%2Fcfm-shared.concord.org%2FeBUpBKFKJzDmxewhRN3O%2Ffile.json 

[Hugo Hernández]

Thank you so very much! This has been very usefull. I had to shorten my x’s values, but that doesn´t make any difference to what I´m aiming

[Bill Finzer]

Hi Hugo,

This doesn’t help in the short term, but I’ve added a request for a C(n,r) function.

Bill

[Hugo Hernández]

Hi, Bill:

I´m glad to hear about you! Thanks so very much; I guess that will be usefull. In the mean time, Dan Damelin above just gave me a very good solution for the work in progress.

I hope to see you in Rosario on September. Take care.

[Bill Finzer]

I dug around a bit and found that CODAP already has a combinations(n,k) function. But you asked for permutations, so perhaps that is no help.

[Hugo Hernández]

I thought you meant Permutations on the last message, since CODAP has combinations already. But happily there’s a way to do the simulation.

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