Re: [Bug-AUCTeX] 11.85; \smash command makes preview image blank

[Tim Toolan]

Quoting "David Kastrup" <address@hidden>:

> "Tim Toolan" <address@hidden> writes:
>
> > Remember to cover the basics.  Including a minimal LaTeX example
> > file exhibiting the problem might help.
> >
> > When using \smash, the preview image is blank.
>
> No, it isn't.  It's smashed.  Has no height.

True, but it stems from a clipping or bounding box problem.  The  
object should still have been drawn in its entirety.

> > A simple example that illustrates this problem is:
> >
> > \documentclass{article}
> > \begin{document}
> > This is not smashed $\tilde{F}$ and this is smashed $\smash{\tilde{F}}$.
> > \end{document}
> >
> > Note that when previewing, the first \tilde{F} will appear correctly,
> > and the second one will be missing.  I am not sure what the best
> > solution to this is, but redefining the \smash command to do nothing
> > before generating the images would probably fix it.
>
> The solution is not to use \smash when you don't mean it.  Otherwise it
> will also cause collisions with text and other things.  There is not
> anything sensible we can do: \smash is used in fractions and other stuff
> for fixing vertical spacing, and we don't want to interfere there.

A more practical example that illustrates the problem follows.  In  
this example, the first paragraph contains a single \smash command to  
correct the interline spacing, and the second paragraph differs only  
by the lack of the \smash command.  Note that although LaTeX believes  
there may be a collision and inserts extra interline space, there is  
clearly no collision, thus the \smash is used to make the paragraph  
look correct.

I am not sure if there is a way to fix this, and I am not sure if it  
occurs with many other characters besides bold capital Fs with a tilde  
above them, but I do know that in a paper that I am writing, I have to  
smash many of my bold capital Fs with tildes above them to prevent the  
paragraphs from looking horrible.

Regards,

Tim

\documentclass{article}
\begin{document}
This is a sentence consisting of a bunch of words, and it is just
filler to make sure that the paragraph has enough words to produce
normal interline spacing.  Since $\tilde{\mathbf{F}}
\tilde{\mathbf{F}}^H = \tilde{\mathbf{U}}_f (\tilde{\mathbf{\Sigma}}
\tilde{\mathbf{\Sigma}}^H) \tilde{\mathbf{U}}_f^H$, the eigenvalues of
foo are the squares of the singular values of foo, and the
eigenvectors of $\smash{\tilde{\mathbf{F}} \tilde{\mathbf{F}}^H}$ are
the left singular vectors of foo.  This is a sentence consisting of a
bunch of words, and it is just filler to make sure that the paragraph
has enough words to produce normal interline spacing.

This is a sentence consisting of a bunch of words, and it is just
filler to make sure that the paragraph has enough words to produce
normal interline spacing.  Since $\tilde{\mathbf{F}}
\tilde{\mathbf{F}}^H = \tilde{\mathbf{U}}_f (\tilde{\mathbf{\Sigma}}
\tilde{\mathbf{\Sigma}}^H) \tilde{\mathbf{U}}_f^H$, the eigenvalues of
foo are the squares of the singular values of foo, and the
eigenvectors of $\tilde{\mathbf{F}} \tilde{\mathbf{F}}^H$ are the left
singular vectors of foo.  This is a sentence consisting of a bunch of
words, and it is just filler to make sure that the paragraph has
enough words to produce normal interline spacing.
\end{document}