Re: evaluating functions and displaying results numerically

*To*: mathgroup at smc.vnet.net*Subject*: [mg126187] Re: evaluating functions and displaying results numerically*From*: prof.eduardofontana at gmail.com*Date*: Tue, 24 Apr 2012 05:31:31 -0400 (EDT)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*References*: <201204210433.AAA29272@smc.vnet.net> <jn0l72$4th$1@smc.vnet.net>

thanks for the replies. I can go along with all your explanations for the Sin function, even though I havent had this interpretation of results from Mathematica before. I never had to use the N option before. What about my second enquire, reproduced below: In another instance, I have a summation of about 1000 terms defined as a function of 3 arguments. When I use numerical arguments to calculate the summation, instead of Mathematica calculating a numerical result it generates a symbolic output with all 1000 terms. It doesnt make sense that Mathematica chooses to do the whole thing symbolically. I have made similar calculations before, and Mathematica performed the calculation numerically. I presume that I have enabled some sort of symbolic calculation mode, but I cannot figure out where. I am attaching a a link to a pdf file showing a image of the generated result for my function called "Absorption". The other functions called by Absorption are defined prior to the definition of Absorption. I just want to show the type of result generated. Also, If I want to plot my function Absorption relative to one of the arguments, Mathematica just doesnt plot it. Best regards The output image is in the google docs file below https://docs.google.com/open?id=0Bw08G8QtolpXUDBnQUswdXUyVE0 Em domingo, 22 de abril de 2012 07h06min26s UTC-3, Murray Eisenberg escreveu: > Correct, the result of Sin[1] is _exactly_ Sin[1], whereas Sin[1.] will > give you a decimal result that approximates the exact value. > > This is one of the most basic ideas of Mathematica -- that it can deal > with exact symbolic quantities, like Pi or E or Sqrt[2] or Sin[1]. > > Perhaps you need to read some of the introductory tutorials provided > with Mathematica. > > On 4/21/12 12:33 AM, Eduardo Fontana wrote: > > Once in a while a face a problem with Mathematica in which I cannot > > get a straightforward numerical output. > > I have a function defined in mathematica, I try to evaluate the > > function with numerical arguments and mathematica returns a replica of > > my function with the same arguments. It must be something I set > > without noticing. I cannot get numerical results at all. > > In another instance, I have a summation of about 1000 terms defined as > > a function of 3 arguments. When I use numerical arguments, instead of > > Mathematica calculating a numerical result it generates a symbolic > > output with all 1000 terms. Even if a try something very simple such > > as > > In[1]: Sin[1] > > the output is > > Out[1]: Sin[1] > > Could anyone give me a clue on this? > > regards > > > > -- > 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**:**evaluating functions and displaying results numerically***From:*Eduardo Fontana <prof.eduardofontana@gmail.com>