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Re: evaluating functions and displaying results numerically

• To: mathgroup at smc.vnet.net
• Subject: [mg126166] Re: evaluating functions and displaying results numerically
• From: "djmpark" <djmpark at comcast.net>
• Date: Sun, 22 Apr 2012 06:07:02 -0400 (EDT)
• Delivered-to: l-mathgroup@mail-archive0.wolfram.com
• References: <13085423.12310.1334983918872.JavaMail.root@m06>

It's because Sin[1] is regarded by Mathematica as an exact expression.
Mathematica can often do manipulations with exact expressions and obtain
exact results. Mathematica does not convert then to approximate numbers
until you use N on them, or mix them with approximate numbers.

Sin[1] // N
0.841471 

And remember that the purpose of N is to convert exact numbers to
approximate numbers and not to format numbers. To format numbers for display
use NumberForm.


David Park
djmpark at comcast.net 
http://home.comcast.net/~djmpark/index.html 



From: Eduardo Fontana [mailto:prof.eduardofontana at gmail.com] 


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