Re: [fricas-devel] Deriving the Poisson distribution, can I

2018-02-08 Thread Waldek Hebisch 
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'.

I am not sure which one is worse: not getting one sided limit
or how we get two sided one.  Namely, 'exprToUPS' contains
"last chance" expander which expands function into series
by taking successive derivatives.  This expander should be
used for computing limits only when we know that there is
an expansion (and when there is an expansion we must be careful
as this expander can fail due to division by 0).  Gruntz-Shackell
routines (mrv_*) perform checks that function is of expected form.
'limit' blindly passes expression to expander...

-- 
  Waldek Hebisch

-- 
You received this message because you are subscribed to the Google Groups 
"FriCAS - computer algebra system" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to fricas-devel+unsubscr...@googlegroups.com.
To post to this group, send email to fricas-devel@googlegroups.com.
Visit this group at https://groups.google.com/group/fricas-devel.
For more options, visit https://groups.google.com/d/optout.

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

2018-01-08 Thread 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"

-- 
You received this message because you are subscribed to the Google Groups 
"FriCAS - computer algebra system" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to fricas-devel+unsubscr...@googlegroups.com.
To post to this group, send email to fricas-devel@googlegroups.com.
Visit this group at https://groups.google.com/group/fricas-devel.
For more options, visit https://groups.google.com/d/optout.

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

2018-01-08 Thread 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'.
>>
>> --
>> 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
>> fricas-devel+unsubscr...@googlegroups.com.
>> To post to this group, send email to fricas-devel@googlegroups.com.
>> Visit this group at https://groups.google.com/group/fricas-devel.
>> For more options, visit https://groups.google.com/d/optout.
>>
>

-- 
You received this message because you are subscribed to the Google Groups 
"FriCAS - computer algebra system" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to fricas-devel+unsubscr...@googlegroups.com.
To post to this group, send email to fricas-devel@googlegroups.com.
Visit this group at https://groups.google.com/group/fricas-devel.
For more options, visit https://groups.google.com/d/optout.

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

2018-01-08 Thread 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
> fricas-devel+unsubscr...@googlegroups.com.
> To post to this group, send email to fricas-devel@googlegroups.com.
> Visit this group at https://groups.google.com/group/fricas-devel.
> For more options, visit https://groups.google.com/d/optout.
>

-- 
You received this message because you are subscribed to the Google Groups 
"FriCAS - computer algebra system" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to fricas-devel+unsubscr...@googlegroups.com.
To post to this group, send email to fricas-devel@googlegroups.com.
Visit this group at https://groups.google.com/group/fricas-devel.
For more options, visit https://groups.google.com/d/optout.

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

2018-01-08 Thread 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'.

-- 
You received this message because you are subscribed to the Google Groups 
"FriCAS - computer algebra system" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to fricas-devel+unsubscr...@googlegroups.com.
To post to this group, send email to fricas-devel@googlegroups.com.
Visit this group at https://groups.google.com/group/fricas-devel.
For more options, visit https://groups.google.com/d/optout.