Re: Re: Simply derivative question, Math 5.

*To*: mathgroup at smc.vnet.net*Subject*: [mg50273] Re: [mg50257] Re: [mg50240] Simply derivative question, Math 5.*From*: Murray Eisenberg <murray at math.umass.edu>*Date*: Tue, 24 Aug 2004 06:22:08 -0400 (EDT)*Organization*: Mathematics & Statistics, Univ. of Mass./Amherst*References*: <200408220419.AAA10290@smc.vnet.net> <200408231034.GAA14653@smc.vnet.net>*Reply-to*: murray at math.umass.edu*Sender*: owner-wri-mathgroup at wolfram.com

Typo: <Esc>ee<Esc>, not <Esc>e<Esc> (the latter yielding epsilon). Murray Eisenberg wrote: > As the Mathematica Book (printed or electronic) explains, ALL built-in > objects in Mathematica have names that begin with an upper-case letter. > So the Napierian "e" is represented by E, not e. (Or, if you want it > to look more like conventional mathematical notation, type Esc e Esc > to obtain the Mathematica stylized e; in fact, you'll see that stylized > e in the result.) > > So Mathematica was treating e as an unknown constant and gave the > correct answer. > > When e = E, then Log[e] = 1, so no "extra" factor: > > D[(1 + c E^t)/(1 - c E^t), t] // Simplify > > By the way, you don't need an explicit multiplication operator after the > c here -- just a space (so Mathematica can see you have two > single-letter names rather than a two-letter name cE). > > It's REALLY worth a couple hours of your time to read the early material > in the Mathematica Book! It will save you a lot of time avoiding such > basic difficulties. > > > Ted Kahn wrote: > >>Hello- I am trying to take the derivative of the following function: >> >>(1 + c*e^t)/(1 - c*e^t) >> >>with respect to t. >> >>================ >>\!\(Simplify[D[\(1 + c\ e\^t\)\/\(1 - c\ e\^t\), t]]\) >>============ >> >>The answer I get includes an "extra" Log[e] in the numerator. Am I not >>using the program correctly or am I not understanding the answer >>correctly? Other? >> >>thanks, -ted > > -- Murray Eisenberg murray at math.umass.edu Mathematics & Statistics Dept. Lederle Graduate Research Tower phone 413 549-1020 (H) University of Massachusetts 413 545-2859 (W) 710 North Pleasant Street fax 413 545-1801 Amherst, MA 01003-9305

**References**:**Simply derivative question, Math 5.***From:*"Ted Kahn" <tedkahn@mindspring.com>

**Re: Simply derivative question, Math 5.***From:*Murray Eisenberg <murray@math.umass.edu>