Re: [fricas-devel] Deriving the Poisson distribution, can I symbolically compute this limit?

[oldk1331]

> I don't want to be to hard on FriCAS since I know this involves 2 variables.

It's not about 2 variables.

p := product((n-i)/n, i=1..(x-1))
limit(p, n=%plusInfinity)

That is equvalent to

p1 := product(1-i*n, i=1..(x-1)) -- eval(p, n = 1/n)
limit(p1, n=0)

FriCAS can handle that limit.
But due to the defect I mentioned, it can handle limit
from both side of 0, but not from one side of 0:

limit(p1, n=0, "right") -- gives "failed"

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Re: [fricas-devel] Deriving the Poisson distribution, can I symbolically compute this limit?

[Kyle Andrews]

FYI, here was the code I was thinking about in my last reply.

map(j +-> limit(eval(p, x=j) :: FRAC(POLY(INT)), n = %plusInfinity), [-5,
0, 1, 15, 20, 23, 30, 50, 100])


On Mon, 8 Jan 2018 at 08:07 Kyle Andrews  wrote:

> Thanks for looking. I don't want to be to hard on FriCAS since I know this
> involves 2 variables. I know I can do better than numeric eval:
>
> If I eval(p, x=30) :: FRAC POLY INT and then take the limit it works, and
> I can map across many x's to check.
>
> But it if course would be nice to check every possible x in one go.
>
> On Mon, Jan 8, 2018, 04:37 oldk1331  wrote:
>
>> It should be solvable:
>>
>> p1 := eval(p, n = 1/n)
>> limit(p1, n = 0)
>>
>> The result is "1^(x-1)"
>>
>> I think this is a bug. There should be something added for 'exprToGenUPS',
>> like r1645 for 'exprToUPS'.
>>
>> --
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>>
>

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Re: [fricas-devel] Deriving the Poisson distribution, can I symbolically compute this limit?

[Kyle Andrews]

Thanks for looking. I don't want to be to hard on FriCAS since I know this
involves 2 variables. I know I can do better than numeric eval:

If I eval(p, x=30) :: FRAC POLY INT and then take the limit it works, and I
can map across many x's to check.

But it if course would be nice to check every possible x in one go.

On Mon, Jan 8, 2018, 04:37 oldk1331  wrote:

> It should be solvable:
>
> p1 := eval(p, n = 1/n)
> limit(p1, n = 0)
>
> The result is "1^(x-1)"
>
> I think this is a bug. There should be something added for 'exprToGenUPS',
> like r1645 for 'exprToUPS'.
>
> --
> You received this message because you are subscribed to a topic in the
> Google Groups "FriCAS - computer algebra system" group.
> To unsubscribe from this topic, visit
> https://groups.google.com/d/topic/fricas-devel/zlKLkJrcddI/unsubscribe.
> To unsubscribe from this group and all its topics, send an email to
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> Visit this group at https://groups.google.com/group/fricas-devel.
> For more options, visit https://groups.google.com/d/optout.
>

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Re: [fricas-devel] Deriving the Poisson distribution, can I symbolically compute this limit?

[oldk1331]

It should be solvable:

p1 := eval(p, n = 1/n)
limit(p1, n = 0)

The result is "1^(x-1)"

I think this is a bug. There should be something added for 'exprToGenUPS',
like r1645 for 'exprToUPS'.

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