limit gets stuck without computing anything

[mwhansen]

 I noticed that for some expressions limit() gets stuck and does not
return to the sage prompt.  It does not seem to be computing anything
since the cpu usage is 0.
 For example in Sage 3.0.6 try:
vars('Ax,Bx,By')
t = -Ax*sin(sqrt(Ax^2)/2)/(sqrt(Ax^2)*sqrt(By^2 + Bx^2))
t.limit(Ax=0,dir='above')

 It just sits there.  And you need to ctrl-c to get the prompt back.
If you set t = -Ax*sin(sqrt(Ax^2)/2)/(sqrt(Ax^2)*sqrt(By^2))
Then do t.limit(Ax=0,dir='above'), you get a message asking if By is
zero or nonzero.

Component: calculus

Issue created by migration from https://trac.sagemath.org/ticket/3790

[mwhansen]

comment:1

Attachment: trac_3790.patch.gz

[sagetrac-mabshoff]

comment:2

Patch looks good to me.

Cheers,

Michael

[sagetrac-mabshoff]

comment:3

Merged in Sage 3.1.alpha1