[PATCH] Fix laplace() with, e.g., sin(t)/t



Hey everyone,

It seems that a recent commit broke laplace() for functions such as sin(t)/t.
 There were a couple of problems in that commit, and I've attached a patch
which fixes this problem for me.  I've also created a tracker[1] as usual.

There are more details in the tracker, but this is what I was getting:

(%i1) laplace(sin(t)/t,t,s);
Maxima encountered a Lisp error:

HACKIT: variable PARM has no value


And this is what I get with my patch:

(%i1) laplace(sin(t)/t,t,s);
                                 %pi
(%o1)                            --- - atan(s)
                                  2

I don't pretend to understand how everything works.  I think my patch does The
Right Thing, but let me know if I missed something!

Thanks,
Kris Katterjohn

[1]
https://sourceforge.net/tracker/?func=detail&aid=3586122&group_id=4933&atid=304933

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