       Re: Guessing "exact" values

• To: mathgroup at smc.vnet.net
• Subject: [mg76228] Re: Guessing "exact" values
• From: "Dana DeLouis" <dana.del at gmail.com>
• Date: Fri, 18 May 2007 06:09:15 -0400 (EDT)

```Hi.  This is not the best solution, but here's one idea I use.
It's not the best solution, because I can't find a way to make Mathematica's
is locked in stone.
Maybe an expert can jump in and make this dynamic.

A number we know nothing about...(??)
n = 6.283185307179586

Set the variable to something you would like to use.  For me...
NumberToSearch = n;

Re-Enter this equation (Shift Enter), and then click the link.

StringReplace["http://bootes.math.uqam.ca/cgi-bin/ipcgi/lookup.\
pl?Submit=GO+&number=#&lookup_type=simple",
"#" :> ToString[Evaluate[NumberToSearch], InputForm,
NumberMarks -> False]]]

The above click shows it might be 2 Pi.

For your example, I took the full value:
n=10.92477796076938

This number didn't work.  Sometimes it won't work if the number is large.
I don't know what "large" means, but the program really works with
fractions.

I decided to divided the number by 3.

NumberToSearch = 10.92477796076938/3
3.641592653589793

If I re-enter the Hyperlink, and click the link, the solution is Pi+1/2.
Multiply by 3 to get your equation.

Reference:  http://pi.lacim.uqam.ca/eng/
--
HTH   :>)
Dana DeLouis
Windows XP & Mathematica 6.0 & Help files 5.2 :>~

"Szabolcs" <szhorvat at gmail.com> wrote in message
news:f2eim0\$t2f\$1 at smc.vnet.net...
> "Another computer algebra system" has a function, identify(), which
> attempts to guess the exact expression that evaluates to a particular
> numerical value.
>
> Example:
>
> In:= N[3Pi+3/2,10]
>
> Out= 10.92477796
>
> > identify(10.92477796);
>                                   3
>                                   - + 3 Pi
>                                   2
>
> Is there a package with similar functionality for Mathematica?
>
> Szabolcs
>

```

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