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Re: ToExpression[..,TexForm] does not seem to work on

  • To: mathgroup at smc.vnet.net
  • Subject: [mg104386] Re: [mg104351] ToExpression[..,TexForm] does not seem to work on
  • From: Bob Hanlon <hanlonr at cox.net>
  • Date: Fri, 30 Oct 2009 02:17:06 -0500 (EST)
  • Reply-to: hanlonr at cox.net

Put a space after sum in the TeX

s = TeXForm[Sum[f[n], {n, 1, m}]]

\sum _{n=1}^m f(n)

Note the space after sum in the above output

ToExpression["\\sum _{n=1}^m f(n)", TeXForm]

Sum[f[n], {n, 1, m}]

ToExpression["\\sum _ {n=1}^m f(n)", TeXForm]

Sum[f[n], {n, 1, m}]


Bob Hanlon

---- "Nasser M. Abbasi" <nma at 12000.org> wrote: 

=============
 Version 7.

Some Latex commands are converted ok to Mathematica expressions, such as:

ToExpression["\\sqrt{3}", TeXForm]
ToExpression["\\frac{a}{b}", TeXForm]

But the next Latex "sum" command does not seem to work. Is this a known 
"issue" or is there a trick for one command?

I take the output of the TexForm command, and then try to convert it back to 
Mathematica expression, but the conversion back fails:

s = TeXForm[Sum[f[n], {n, 1, m}]]
ToExpression[ToString[s], TeXForm]

Even when I type the Latex output by hand, it does not work:

ToExpression["\\sum_{n=1}^m f(n)", TeXForm]

the error is :

Syntax::sntxi:Incomplete expression; more input is needed.
ToExpression::esntx:Could not parse \sum_{n=1}^m f(n) as Mathematica input.

--Nasser 



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