Musings and comments about our common interest

Published on by JGD
## More random number generator according to different statistical distributions for HP Prime

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On the day of the presentation of the new firmware, Tim Wessmann from HP posted a list of the improvements that had been implemented in it. Among them, there were both new density and cumulated statistical distribution functions, and random generators following said distributions. This made the Prime much more appropriated for deep statistical analysis, montecarlo tests and simulations, and saved a lot of programming time for those who needed. I have already mentioned in the blog that HPmuseum user Salvomic generated a substantial number of programs to create different distributions. But now, according to Tim, this would not be necessary. Or would it?

Here is what was mentioned in the post:

New Functionality (Calculator Software)

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- Added more distribution functions – density/cumulative/inverse: beta, exponential, gamma, geometric, negbinomial, uniform, weibull
- Added more random generation functions: binomial, chisquare, fisher, geometric, poisson, student

Well, when you try to find a function, you go to the toolbox key. Then I press Math -> Probability -> Random, and I get the following list:

- Number
- Integer
- Normal
- Seed

Very far from the list. Let’s get some help for one of them, for example the normal distribution. Clicking on it, it comes to the entry line, and pressing the help button, you get to the help for that item. There is a useful button on the lower right, “other”, that links to related functions. Will them be there?

Nope! It only shows the other three of the list. So wasn’t Tim right?

User Salvomic directed me to where I should have started: the function catalog. I avoided it since there are all functions there, and even scrolling, it takes you a lot of time to navigate it! But if you just press the first letter of the function, it will advance up to that letter. Ok, but what’s the name of the function? I guessed they would start by R (from Random), and there were they!:

- randbinomial,
- randchisquare
- randexp
- randfischer
- randgeometric
- randnorm
- randpoisson
- randstudent

The fact that they are lower letter functions means that they are used in the CAS environment, or in the home area but preceded by “CAS.”