I think there may also be other issues with pdf generation in the signal package.


With the checked out repo, running make doc, to ensure I have the generated files and then from the doc filder running

texi2pdf signal.texi

[2] (/home/jade/octave-packages/octave-signal/doc/functions.texi
Writing index file signal.fn

Overfull \hbox (24.7901pt too wide) in paragraph at lines 85--85
 [] @texttt specgram (chirp ([0:0.001:5]));  # default linear chirp of 0-100Hz
in 1 sec[]
/home/jade/octave-packages/octave-signal/doc/functions.texi:93: @group invalid
in context where filling is enabled.
@group ...lid in context where filling is enabled}
                                                  @fi @startsavinginserts @s...
l.93 @group

?
/home/jade/octave-packages/octave-signal/doc/functions.texi:93: Emergency stop.

@group ...lid in context where filling is enabled}
                                                  @fi @startsavinginserts @s...
l.93 @group

/home/jade/octave-packages/octave-signal/doc/functions.texi:93:  ==> Fatal error occurred, no output PDF file produced!

I will take a look at what else isnt working

In file inst/xcorr.m, we see the following:

## @tex
## $$   R_{xy}(k) = \sum_{i=1}^{N} x_{i+k} \conj(y_i),
## @end tex

I think it should be:

## @tex
## $$   R_{xy}(k) = \sum_{i=1}^{N} x_{i+k} \overline{y_i}, $$
## @end tex

The \conj command does not exist in TeX. The appropriate way of representing the conjugation in TeX is by using the \overline macro.
 
Furthermore, the closing tag $$ is lacking.

The patch attached to this bug report fixes the problem. Withoout applying it, it is not possible to build the PDF form of documentation for the package.