Norman, I've been an engineer for 25 yrs and have never needed a dble factorial. Looks to be something used in discrete variable calculus (finite differences). A brief look in some old text books, however, didn't yield any specific reference.
> Norman, > I've been an engineer for 25 yrs and have never needed a > dble factorial. Looks to be something used in discrete > variable calculus (finite differences). A brief look in > some old text books, however, didn't yield any specific > reference.
> Sorry, I'm afraid this isn't much help.
> Jay > >-----Original Message----- > >Hi!
> >I'm writing some material on functions. Has anyone used > the FACTDOUBLE > >function?
> >I've looked in my maths and stats (limited) library but > find no references > >to it.
> >I know what is does (Help is quite useful). But why use > it?
> >tia
> >-- > >Norman Harker > >Senior Lecturer, Real Estate Investment Analysis and > Feasibility Studies > >University of Western Sydney.
>It seems to be very little used and I still can't find any references to >double factorials.
>Sees Ya! >"Jay T. Emory" <jte...@aol.com> wrote in message >news:1cf501c0fb1f$95481120$9be62ecf@tkmsftngxa03... >> Norman, >> I've been an engineer for 25 yrs and have never needed a >> dble factorial. Looks to be something used in discrete >> variable calculus (finite differences). A brief look in >> some old text books, however, didn't yield any specific >> reference.
>> Sorry, I'm afraid this isn't much help.
>> Jay >> >-----Original Message----- >> >Hi!
>> >I'm writing some material on functions. Has anyone used >> the FACTDOUBLE >> >function?
>> >I've looked in my maths and stats (limited) library but >> find no references >> >to it.
>> >I know what is does (Help is quite useful). But why use >> it?
>> >tia
>> >-- >> >Norman Harker >> >Senior Lecturer, Real Estate Investment Analysis and >> Feasibility Studies >> >University of Western Sydney.
> asin x = x + sum {1*3*5*...*(2n-1)/[2*4*6*...*(2*n)*(2*n+1)]}*x^(2*n+1)
> Sum from n=1 to infinity
> Norman Harker wrote in message ... > >Thank Jay!
> >It seems to be very little used and I still can't find any references to > >double factorials.
> >Sees Ya! > >"Jay T. Emory" <jte...@aol.com> wrote in message > >news:1cf501c0fb1f$95481120$9be62ecf@tkmsftngxa03... > >> Norman, > >> I've been an engineer for 25 yrs and have never needed a > >> dble factorial. Looks to be something used in discrete > >> variable calculus (finite differences). A brief look in > >> some old text books, however, didn't yield any specific > >> reference.
> >> Sorry, I'm afraid this isn't much help.
> >> Jay > >> >-----Original Message----- > >> >Hi!
> >> >I'm writing some material on functions. Has anyone used > >> the FACTDOUBLE > >> >function?
> >> >I've looked in my maths and stats (limited) library but > >> find no references > >> >to it.
> >> >I know what is does (Help is quite useful). But why use > >> it?
> >> >tia
> >> >-- > >> >Norman Harker > >> >Senior Lecturer, Real Estate Investment Analysis and > >> Feasibility Studies > >> >University of Western Sydney.
I think his point is that it is useful in numerical analysis.
Some people whant to know how the TV works, others just want to watch it. They don't have to know the theory to just watch TV; but the theory still has a big impact on their life even if it is of no direct importance to them.
> > asin x = x + sum {1*3*5*...*(2n-1)/[2*4*6*...*(2*n)*(2*n+1)]}*x^(2*n+1)
> > Sum from n=1 to infinity
> > Norman Harker wrote in message ... > > >Thank Jay!
> > >It seems to be very little used and I still can't find any references to > > >double factorials.
> > >Sees Ya! > > >"Jay T. Emory" <jte...@aol.com> wrote in message > > >news:1cf501c0fb1f$95481120$9be62ecf@tkmsftngxa03... > > >> Norman, > > >> I've been an engineer for 25 yrs and have never needed a > > >> dble factorial. Looks to be something used in discrete > > >> variable calculus (finite differences). A brief look in > > >> some old text books, however, didn't yield any specific > > >> reference.
> >> asin x = x + sum {1*3*5*...*(2n-1)/[2*4*6*...*(2*n)*(2*n+1)]}*x^(2*n+1)
> >> Sum from n=1 to infinity > >> >> >Senior Lecturer, Real Estate Investment Analysis and > >> >> Feasibility Studies > >> >> >University of Western Sydney.
Hmmm. According to Help, that's not the way Excel calculates Factdouble. We agree that 3 couples can be arranged in 1*2*3*(2^3) ways (=2*4*6), but Excel supposedly calculates Factdouble(3) as 1*3.
From Help:
Examples
FACTDOUBLE(6) equals 48
FACTDOUBLE(7) equals 105
- David Hilberg
On Sat, 23 Jun 2001 19:07:06 +0300, "Eero Tibar" <e...@matti.ee> wrote:
>>> asin x = x + sum {1*3*5*...*(2n-1)/[2*4*6*...*(2*n)*(2*n+1)]}*x^(2*n+1)
>>> Sum from n=1 to infinity >>> >> >Senior Lecturer, Real Estate Investment Analysis and >>> >> Feasibility Studies >>> >> >University of Western Sydney.
_____________ Please reply to newsgroups for follow-up; For personal messages, remove "nöspäm" from address.
> Hmmm. According to Help, that's not the way Excel calculates > Factdouble. We agree that 3 couples can be arranged in 1*2*3*(2^3) > ways (=2*4*6), but Excel supposedly calculates Factdouble(3) as 1*3.
> From Help:
> Examples
> FACTDOUBLE(6) equals 48
> FACTDOUBLE(7) equals 105
> - David Hilberg
> On Sat, 23 Jun 2001 19:07:06 +0300, "Eero Tibar" <e...@matti.ee> > wrote:
> >Ok > >If you want a real-life example then here it goes:
> >N couples were lined up in front of a theatre, each couple together. This > >could have happened in 2*4*6*...*(2*n) ways.
> >Norman Harker wrote in message ... > >>Sorry Eero!
> >>> Sum from n=1 to infinity > >>> >> >Senior Lecturer, Real Estate Investment Analysis and > >>> >> Feasibility Studies > >>> >> >University of Western Sydney.
> _____________ > Please reply to newsgroups for follow-up; For personal messages, > remove "nöspäm" from address.
Hm, sorry I missed this in the last days. For a reference, see the seminal 4-volume set by Johnson and Kotz (1ed.) or the 2nd ed. by J, K and Kemp. First volume (Univariate Discrete Distributions) has some preliminaries for the set. Double Factorial, written as k!!, is described on page 2.
Dave Braden
In article <zFNZ6.11642$qJ4.474...@ozemail.com.au>, "Norman Harker" <nhar...@ozemail.com.au> wrote:
> Sees Ya! > "David Hilberg" <davidh@nöspäm.ericmarder.com> wrote in message > news:3b376954.6829211@news2.fcc.net... > > Hmmm. According to Help, that's not the way Excel calculates > > Factdouble. We agree that 3 couples can be arranged in 1*2*3*(2^3) > > ways (=2*4*6), but Excel supposedly calculates Factdouble(3) as 1*3.
> > From Help:
> > Examples
> > FACTDOUBLE(6) equals 48
> > FACTDOUBLE(7) equals 105
> > - David Hilberg
> > On Sat, 23 Jun 2001 19:07:06 +0300, "Eero Tibar" <e...@matti.ee> > > wrote:
> > >Ok > > >If you want a real-life example then here it goes:
> > >N couples were lined up in front of a theatre, each couple together. > This > > >could have happened in 2*4*6*...*(2*n) ways.
> > >Norman Harker wrote in message ... > > >>Sorry Eero!
> > >>> asin x = x + sum > {1*3*5*...*(2n-1)/[2*4*6*...*(2*n)*(2*n+1)]}*x^(2*n+1)
> > >>> Sum from n=1 to infinity > > >>> >> >Senior Lecturer, Real Estate Investment Analysis and > > >>> >> Feasibility Studies > > >>> >> >University of Western Sydney.
> > _____________ > > Please reply to newsgroups for follow-up; For personal messages, > > remove "nöspäm" from address.
> Hm, sorry I missed this in the last days. For a reference, see the > seminal 4-volume set by Johnson and Kotz (1ed.) or the 2nd ed. by J, K > and Kemp. First volume (Univariate Discrete Distributions) has some > preliminaries for the set. Double Factorial, written as k!!, is > described on page 2.
> Dave Braden
> In article <zFNZ6.11642$qJ4.474...@ozemail.com.au>, > "Norman Harker" <nhar...@ozemail.com.au> wrote:
> > Thanks David!
> > That puts me back to square A1.
> > Sees Ya! > > "David Hilberg" <davidh@nöspäm.ericmarder.com> wrote in message > > news:3b376954.6829211@news2.fcc.net... > > > Hmmm. According to Help, that's not the way Excel calculates > > > Factdouble. We agree that 3 couples can be arranged in 1*2*3*(2^3) > > > ways (=2*4*6), but Excel supposedly calculates Factdouble(3) as 1*3.
> > > From Help:
> > > Examples
> > > FACTDOUBLE(6) equals 48
> > > FACTDOUBLE(7) equals 105
> > > - David Hilberg
> > > On Sat, 23 Jun 2001 19:07:06 +0300, "Eero Tibar" <e...@matti.ee> > > > wrote:
> > > >Ok > > > >If you want a real-life example then here it goes:
> > > >N couples were lined up in front of a theatre, each couple together. > > This > > > >could have happened in 2*4*6*...*(2*n) ways.
> > > >Norman Harker wrote in message ... > > > >>Sorry Eero!
> > > >>But are you pulling my leg?
> > > >>=asin(0.5) returns 0.523598776 will do me.
Er, Norman, that may be stretching it a bit. I have only seen double factorials come up a couple of times in 20 years of stats; I wonder what niche of problems even led to their adoption?
dave Braden
In article <2Ic_6.12375$qJ4.504...@ozemail.com.au>, "Norman Harker" <nhar...@ozemail.com.au> wrote:
> "David J. Braden" <dbra...@rochester.rr.com> wrote in message > news:dbraden-841D40.20095226062001@msnews.microsoft.com... > > Hm, sorry I missed this in the last days. For a reference, see the > > seminal 4-volume set by Johnson and Kotz (1ed.) or the 2nd ed. by J, K > > and Kemp. First volume (Univariate Discrete Distributions) has some > > preliminaries for the set. Double Factorial, written as k!!, is > > described on page 2.
> > > Sees Ya! > > > "David Hilberg" <davidh@nöspäm.ericmarder.com> wrote in message > > > news:3b376954.6829211@news2.fcc.net... > > > > Hmmm. According to Help, that's not the way Excel calculates > > > > Factdouble. We agree that 3 couples can be arranged in 1*2*3*(2^3) > > > > ways (=2*4*6), but Excel supposedly calculates Factdouble(3) as 1*3.
> > > > From Help:
> > > > Examples
> > > > FACTDOUBLE(6) equals 48
> > > > FACTDOUBLE(7) equals 105
> > > > - David Hilberg
> > > > On Sat, 23 Jun 2001 19:07:06 +0300, "Eero Tibar" <e...@matti.ee> > > > > wrote:
> > > > >Ok > > > > >If you want a real-life example then here it goes:
> > > > >N couples were lined up in front of a theatre, each couple together. > > > This > > > > >could have happened in 2*4*6*...*(2*n) ways.
> > > > >Norman Harker wrote in message ... > > > > >>Sorry Eero!
> > > > >>But are you pulling my leg?
> > > > >>=asin(0.5) returns 0.523598776 will do me.
> Er, Norman, that may be stretching it a bit. I have only seen double > factorials come up a couple of times in 20 years of stats; I wonder what > niche of problems even led to their adoption?
> dave Braden
> In article <2Ic_6.12375$qJ4.504...@ozemail.com.au>, > "Norman Harker" <nhar...@ozemail.com.au> wrote:
> > Thanks David!
> > I just knew there had to be some use for it.
> > "David J. Braden" <dbra...@rochester.rr.com> wrote in message > > news:dbraden-841D40.20095226062001@msnews.microsoft.com... > > > Hm, sorry I missed this in the last days. For a reference, see the > > > seminal 4-volume set by Johnson and Kotz (1ed.) or the 2nd ed. by J, K > > > and Kemp. First volume (Univariate Discrete Distributions) has some > > > preliminaries for the set. Double Factorial, written as k!!, is > > > described on page 2.
> > > > Sees Ya! > > > > "David Hilberg" <davidh@nöspäm.ericmarder.com> wrote in message > > > > news:3b376954.6829211@news2.fcc.net... > > > > > Hmmm. According to Help, that's not the way Excel calculates > > > > > Factdouble. We agree that 3 couples can be arranged in 1*2*3*(2^3) > > > > > ways (=2*4*6), but Excel supposedly calculates Factdouble(3) as 1*3.
Norm, Let's Keep in mind that FACTDOUBLE is part of the Analysis ToolPak. Given that, I am not perplexed that something of little import appears in my Excel setup. What a find, Norman! It's sort of like the realization that there are so many ways to do a regression within Excel, and that they are internally inconsistent in some cases. IMO, the product really lost a lot of focus by adding poorly-implemented bells and whistles instead of repairing the foundation.
Hmm, that said, I guess I can expect my MSDN shipments to get "lost"?
Dave Braden
In article <9ng_6.12986$qJ4.508...@ozemail.com.au>, "Norman Harker" <nhar...@ozemail.com.au> wrote:
> It doesn't surprise me. Apart from a fairly thorough internet search I also > asked our professors of Maths and Stats and drew a blank.
> But I can't believe that the function was included without some fairly > useful application.
> "David J. Braden" <dbra...@rochester.rr.com> wrote in message > news:dbraden-5CE3B2.01380327062001@msnews.microsoft.com... > > Er, Norman, that may be stretching it a bit. I have only seen double > > factorials come up a couple of times in 20 years of stats; I wonder what > > niche of problems even led to their adoption?
> > > I just knew there had to be some use for it.
> > > "David J. Braden" <dbra...@rochester.rr.com> wrote in message > > > news:dbraden-841D40.20095226062001@msnews.microsoft.com... > > > > Hm, sorry I missed this in the last days. For a reference, see the > > > > seminal 4-volume set by Johnson and Kotz (1ed.) or the 2nd ed. by J, K > > > > and Kemp. First volume (Univariate Discrete Distributions) has some > > > > preliminaries for the set. Double Factorial, written as k!!, is > > > > described on page 2.
> > > > > Sees Ya! > > > > > "David Hilberg" <davidh@nöspäm.ericmarder.com> wrote in message > > > > > news:3b376954.6829211@news2.fcc.net... > > > > > > Hmmm. According to Help, that's not the way Excel calculates > > > > > > Factdouble. We agree that 3 couples can be arranged in 1*2*3*(2^3) > > > > > > ways (=2*4*6), but Excel supposedly calculates Factdouble(3) as > 1*3.
> > > > > > >Ok > > > > > > >If you want a real-life example then here it goes:
> > > > > > >N couples were lined up in front of a theatre, each couple > together. > > > > > This > > > > > > >could have happened in 2*4*6*...*(2*n) ways.
> > > > > > >Norman Harker wrote in message ... > > > > > > >>Sorry Eero!
> > > > > > >>But are you pulling my leg?
> > > > > > >>=asin(0.5) returns 0.523598776 will do me.
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