Re: evaluating functions and displaying results numerically

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• 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

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

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