Mikhail Drugov

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17 years, 71 days

MaplePrimes Activity

These are replies submitted by Mikhail Drugov


And also learning about MathML.

Thank you so much! It was bugging me for so long...

I am not sure I fully understand these different ways (and I find the whole system that you don't really see what you have---as opposed to Latex, say---not very helpful) but they work!


Thank you!

But I wonder how one puts an asterisk as a superscript in the axis label? I have tried many things (do not want to reproduce them here to save space) but either get ^*, or the asteriks is replaced by the upper bar, or some error.

@tomleslie  You are right, of course! I did not notice the third dot. I am very sorry for posting such a trivial question.

@Joe Riel You are right, of course! I did not notice the third dot. I am very sorry for posting such a trivial question.


Thank you!

And one question: In both files you use

dist := Distribution(PDF = (t -> PDF(U, t)), CDF = (t -> CDF(U, t))):
Y    := RandomVariable(dist):

But wouldn't using either PDF or CDF be enough?


Thank you!

I think I came across Gamma Distribution and probably some others where the choice of parametrization in Maple was not the most obvious.


Yes, a bug. Returning zero instead of unevaluated, error, whatever, is very dangerous.


This is extremely helpful, thank you very much!

So, this is not a bug but a very non-intuitive behaviour. I would imagine that either Maple considers Y to be a random variable and then all functions should work, or the opposite, and none should work. But this partial work (PDF, CDF, Variance, etc work) is quite confusing.

It also means that defining a random variable as a function of other random variables is not very straighforward. And also that  Maple help is sometimes confusing. Say, here https://de.maplesoft.com/support/help/maple/view.aspx?path=Statistics%2fRandomVariables in (15) any reasonable person would think that X/Y is Cauchy(0,1) random variable, not some strange object of which function PDF gives the same answer (and again, HazardRate(X/Y,t) always returns zero).

On your last point: "To return to your answer to vv, even if Statistics is a good package (I agree with vv), it still suffers from several flaws (I have already pointed out some of them in the past)."

could you please provide links? I am a heavy user of the Statistics package, and this will be very useful.

Thank you!




Sure, in this particular case I noticed it does not work while writing explicitly f/(1-F) does. But now I wonder which other functions of the Statistics package might have this problem? Or suppose somebody uses it without realizing (maybe, in an expression, maybe, a student),

If this is a bug, it should be reported (I don't know how to do it).

@Carl Love 

This is very good, thank you! I also need other combinations (like 1/4*X1+3/4*X2) and they all work when in this simplest form fraction.



Thank you! This helps! Though if I do for Beta(5,5) then again there is negative pdf in the right tail but then setting Digits:=20: helps. And for Beta(10,10) I need about 40 digits.

@Daniel Skoog 


I just need to get the 2018 version then...




Thank you!

I guess I could also create an image from the text which then can be rotated. It is a pity there is no simple solution...

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