Hi all. This is my first post to the discussions groups I've been
following for the last 4 months.  I used Sage in my first semester
calculus class this last semester, and plan to move every class I can
over to Sage during the next few years.  Giving the students something
they can use anywhere they go without forking over thousands of
dollars has a huge advantage.  As such, I'm going to start doing a
better job of posting errors when they arise and I can't figure out
how to resolve them.

Here is the issue.  When I evaluate

sage: var('t')
sage: integrate(sec(t)*tan(t),t,0,pi/3)

I get the error message

>Traceback (click to the left for traceback)
>...
>Is  cos(t)  positive, negative, or zero?

I can get the correct solution of 1 by executing

sage: var('t')
sage: F(t)=integrate(sec(t)*tan(t),t)
sage: F(pi/3)-F(0)

Similar issues arise with other trig functions.  The command

sage: integrate(csc(x)*cot(x),x,pi/3,pi/2)

gives the error message

>Traceback (click to the left for traceback)
>...
>Is  sin(x)  positive, negative, or zero?

Any ideas why Sage cannot complete this definite integral? I would
prefer to have Sage give the answers without using an assuming
commands, since by specifying the bounds are between 0 and pi/3 I am
already declaring cos(x)>0 and x to be real.

Could this be related to
http://trac.sagemath.org/sage_trac/ticket/6956

Thanks for the great product.

Ben Woodruff
BYU-Idaho

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