Confusing error message from desolve_laplace

[Jean]

Hello Sage-lovers,

While playing with SAGE and Dr. Joyner's tutorial on Sage and DE (dated 11-22-2007), I had a rather confusing error message. At some point, I forgot to put the dependent var in desolve_laplace(), which resulted in the message "... takes at least 2 arguments (2 given)".

sage: t=var('t')
sage: y=function('y',t)
sage: de = lambda x: diff(x,t,t) + x - 1
sage: desolve_laplace(de(y),y)

(y(0) - 1)*cos(t) + sin(t)*D[0](y)(0) + 1
sage: desolve_laplace(de(y),y,ics=[0,0,1])
sin(t) - cos(t) + 1


sage: desolve_laplace(de(y),ics=[0,0,1])
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-6-c8674712d431> in <module>()
----> 1 desolve_laplace(de(y),ics=[Integer(0),Integer(0),Integer(1)])


TypeError: desolve_laplace() takes at least 2 arguments (2 given)

I was a bit surprised by this message. That's clearly not a bug, but I think it would gain by being clearer ("missing dvar" or something.)

And I take this opportunity to thank everybody involved into this project: this is a super great software.

J. :-)

[Jean]

I forgot: I am using SAGE version 5.9

sage: version()
'Sage Version 5.9, Release Date: 2013-04-30'