# How do I change the $\xi$ symbol in mathpazo

I don't like the $\xi$ symbol that mathpazo comes with, so I want to go back to Computer Modern for that symbol alone. How can I do this?

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You should follow the instructions listed in Importing a Single Symbol From a Different Font. – Werner Oct 5 '12 at 22:41
I looked at that question, but I'm not sure how to find what number the \xi symbol is in the letters symbols – Moderat Oct 5 '12 at 22:43

The code is in fontmath.ltx:

\DeclareMathSymbol{\xi}{\mathord}{letters}{"18}


To make the change you want, you can fetch the CM definition of letters and change it into

\DeclareSymbolFont{CMletters}{OML}{cmm}{m}{it}


and then

\DeclareMathSymbol{\xi}{\mathord}{CMletters}{"18}

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Worked! Thanks for the help – Moderat Oct 5 '12 at 22:58
when i use \DeclareSymbolFont{CMlargesymbols}{OMX}{cmex}{m}{n}‎‎‎ \DeclareMathSymbol{\‎‏‎sum‎}{\mathop}{CMlargesymbols}{"50}‎‎‎, it results an error: "Command '\sum' already defined". how can i change the sum symbol? – smh Dec 7 '12 at 10:03
@smh I don't get this error; please, open a new question, with a link to this one, adding a minimal example producing the error. – egreg Dec 7 '12 at 12:13