"Typeset" problem with sech(x)

[TianWei]

Hi, I'm new to Sage and came across a potential bug in the Sage
Notebook. When the "Typeset" checkbox is on, the expression "sech(x)"
evaluates to an error:

Unknown control sequence '\sech'

The error text is contained in a pink box with a thin red border. When
"Typeset" is off, there is no problem (it evaluates to the expected
"sech(x)")

This happened in the Sage Notebook with Mozilla Firefox 3.0.14. I'm
running Sage version 4.1.2 on Ubuntu 9.04 as a guest operating system
in VMware Workstation 6.5.3, on a Windows XP host. I compiled Sage
from the source code.

I'm a novice programming/math hobbyist, so any help and advice is very
much appreciated.

Thanks,
TianWei

[Marshall Hampton]

Latex doesn't actually support \sech, so this can't really be
considered an error on Sage's part.

Note that

sage: latex('sech(x)')

gives

\text{sech(x)}

for this reason. This does seem a little odd, since Latex (and
jsmath, which is what typesets things in the notebook) does support
cosh, sinh, and tanh.

-Marshall Hampton

[John H Palmieri]

On Oct 25, 7:37 pm, Marshall Hampton <hampto...@gmail.com> wrote:
> Latex doesn't actually support \sech, so this can't really be
> considered an error on Sage's part.
>
> Note that
>
> sage: latex('sech(x)')
>
> gives
>
> \text{sech(x)}

On the other hand,

sage: latex(sech)

gives

\sech

I think the problem is in sage/functions/hyperbolic.py:

PrimitiveFunction.__init__(self, "sech", latex=r"\sech",
approx=lambda x: 1/math.cosh(x))

Which hyperbolic functions have broken latex methods?

John

[Burcin Erocal]

Hi,

Here is the relevant ticket:

http://trac.sagemath.org/sage_trac/ticket/6286

In the symbolic function refactoring patch [1], I fixed the problems
with sin^{-1}. It seems that \sech still remains

[1] http://groups.google.com/group/sage-devel/browse_thread/thread/6f1efcad26909d3

I will try to clean up the symbolic functions patch next week and
submit it for review. I can try to fix the other typesetting problems
then if nobody beats me to it.

Cheers,
Burcin