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Re: Incompletely simplified Square root.

• To: mathgroup at smc.vnet.net
• Subject: [mg121073] Re: Incompletely simplified Square root.
• From: Paul von Hippel <paulvonhippel at yahoo.com>
• Date: Fri, 26 Aug 2011 05:23:42 -0400 (EDT)
• Delivered-to: l-mathgroup@mail-archive0.wolfram.com
• References: <201108251104.HAA24880@smc.vnet.net> <C57A4BC6-3DE6-426C-8C2D-03A19E2D51F2@mimuw.edu.pl>
• Reply-to: Paul von Hippel <paulvonhippel at yahoo.com>

PolynomialForm served a useful purpose in an previous step, when the expression was a polynomial. I didn't realize it would remain attached to the expression and cause trouble in this way.



________________________________
From: Andrzej Kozlowski <akoz at mimuw.edu.pl>
To: paulvonhippel at yahoo <paulvonhippel at yahoo.com>
Cc: mathgroup at smc.vnet.net
Sent: Thursday, August 25, 2011 1:47 PM
Subject: [mg121073] Re: [mg121050] Incompletely simplified Square root.



On 25 Aug 2011, at 13:04, paulvonhippel at yahoo wrote:

> Can someone tell me why the following input doesn't produce an output
> of 0.68....?
> Why is the output under the radical? Thanks!
> 
> In[574]:= Sqrt[\!\(\*
> TagBox[
> FractionBox["926", "2025"],
> PolynomialForm]\)] // N
> 
> Out[574]= Sqrt[\!\(\*
> TagBox["0.45728395061728394`",
> PolynomialForm]\)]
> 

Because PolynomialForm[926/2025] is not a number so you can't extract a square root of it or even perform any arithmetical operations on it. For example, try
1 + PolynomialForm[926/2025].

The same will be true with any other "Forms", e.g.

1 + InputForm[1]

InputForm[1] + 1

You have obviously misunderstood what these wrappers are. Also, why are you using PolynomialForm in this way, anyway, it's obviously not doing anything useful?

Andrzej Kozlowski

• Follow-Ups:
  • Re: Incompletely simplified Square root.
    • From: Murray Eisenberg <murray@math.umass.edu>
  • Re: Incompletely simplified Square root.
    • From: Murray Eisenberg <murray@math.umass.edu>

• References:
  • Incompletely simplified Square root.
    • From: paulvonhippel at yahoo <paulvonhippel@yahoo.com>