Text Formatting ⇒ Illegal parameter in definition of \reserved@a. \crcr

[latexforever]

Hello,

I had decided to modify all my

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\vec{}

commands into

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\overrightarrow{}

in commands (I have evidently the amsmath package).

I applicated it in one of my big documents, and it worked perfectly. Anyway, in another document, it does not work at all, and I receive, at compilation:

Illegal parameter in definition of \reserved@a. \crcr every time I use

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\overrightarrow{}

command. As it is a Physics document, you understand why I directly receive 545 errors because of this.

Can somebody tell me why it displays this error message? Thanks.

[Stefan Kottwitz]

Hi,

try \protect before \overrightarrow.

Stefan

[latexforever]

Before all? It has no influence at all.

[Stefan Kottwitz]

Yes, before each \overrightarrow. \overrightarrow is a fragile command that might need to be protected. Alternatively you could make it robust using fixltx2e:

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\usepackage{fixltx2e}
\MakeRobust{\overrightarrow}

Stefan

[latexforever]

Yes, but it still changes nothing in my recurrent error.

[Stefan Kottwitz]

It could fix this error for instance if \overrightarrow was used in a \caption parameter.
If it's not working in your case then show us at least an line that's raising the error.

Stefan

[latexforever]

Simply

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$\overrightarrow{AB}$

.

[Stefan Kottwitz]

Sure? Is this really a complete line of your code where that error occurs, right at that place? Not inside braces {} as parameter for other macros? This code piece itself shows no problem.

Stefan

[latexforever]

Yes, sure. That was weird, and that's why I posted my question.

It now works, but I still don't understand why.

I added

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\usepackage[protrusion=true,draft=false,final,verbose=true,babel=true]{microtype}

in my preamble, moved

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\usepackage[Rejne]{fncychap}

just after

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\usepackage[subfigure]{tocloft}

and put

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\usepackage{fixltx2e}
\MakeRobust{\overrightarrow}

just after the microtype call.

I also erased the .aux file, but I had already done this before writing this post (sometimes, the .aux file is not always ``clean'', and it needs to be completely re-generated, I think: can you confirm it?).

Thanks!