       Re: Re: Hold and Equal

• To: mathgroup at smc.vnet.net
• Subject: [mg73769] Re: [mg73734] Re: Hold and Equal
• From: Murray Eisenberg <murray at math.umass.edu>
• Date: Wed, 28 Feb 2007 04:28:03 -0500 (EST)
• Organization: Mathematics & Statistics, Univ. of Mass./Amherst
• References: <erufqm\$s7j\$1@smc.vnet.net> <200702271041.FAA23729@smc.vnet.net>

```Unfortunately, such a ToString expression does not produce properly
formatted mathematical text, where the powers are shown as actual
superscripts.

dh wrote:
> Hi Murray,
>
> a quick and dirty solution that does not create evaluation problems is
>
> to convert your expression into a string and make the replacement there:
>
> fun[x_]:= StringReplace[ToString[x], "==" -> "="]
>
> if you now say: fun[(a + b)^2 == Expand[(a + b)^2]] you get:
>
>         2     2            2
>
> (a + b)  = a  + 2 a b + b
>
>
>
> Daniel
>
>
>
> Murray Eisenberg wrote:
>
>> How can I produce in an Output cell (under program control) an
>
>> expression like the following,
>
>
>>    (a+b)^2 = a^2+ 2 a b + b^2
>
>
>> where instead of the usual Equal (==) I get a Set (=), as in traditional
>
>> math notation?  I want to input the unexpanded (a+b)^2 and have the
>
>> expansion done automatically.
>
>
>> Of course, I can try something like the following:
>
>
>>    (a+b)^2 == Expand[(a+b)^2])
>
>
>> So how do I convert the == to =?  Of course
>
>
>>    ((a + b)^2 == Expand[(a + b)^2]) /. Equal -> Set
>
>
>> gives a Set::write error.  And
>
>
>>    (Hold[(a + b)^2 == Expand[(a + b)^2]]) /. Equal -> Set
>
>
>> doesn't actually evaluate the Expand part and leaves the "Hold" wrapper.
>
>
>
>
>
>
>

--
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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