[OS X TeX] help

Ari Stern ari at caltech.edu
Fri Feb 29 05:58:17 CET 2008

> 1) I suppose that [ ...... ] stands for a sequence of lines to be
>  commented and that square brackets are not needed.

Yes, that's correct.  I probably could have been more clear -- the
brackets and ellipses are not necessary.  All you need to do is put
\iffalse before the block of text and \fi at the end of the block.

>  2) But what has to be false ? In other words, under what conditions
>  will the block of lines be ignored by the compiler?

The \iffalse ... \fi block means the following, in terms of C-style code:

if (false) {

Since the argument is always "false," the compiler never enters this
block of code, no matter what.  (I think I see where the confusion is,
though.  The "false" in \iffalse is not logical negation, as in,
"statement x is false."  Rather, it is the boolean value FALSE.)

>  3)  When I commented a block of lines they were ignored
>  unconditionally. What Ari is proposing seems to be different in that
>  respect. Right or wrong?

Wrong: \iffalse ... \fi will ignore the enclosed text unconditionally.
 Hope this helps!


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