Martin R wrote:
>
> Nasser found the following interesting bug at
> https://trac.sagemath.org/ticket/25905:
>
> (1) -> f := (I*a*tan(d*x + c) + a)^3*tan(d*x + c)
>
> (1)
> 3 3 4 2 3 3 3 2
> I a tan(d x + c) + 3 I a tan(d x + c) + 3 I a tan(d x + c)
> +
> 3
> a tan(d x + c)
> Type:
> Expression(Integer)
> (2) -> F := integrate(f, x)
>
> (2)
> 2 3 1 3 3 3
> (9 I - 3)a log(-----------------) + 2 I a tan(d x + c)
> 2
> tan(d x + c) + 1
> +
> 2 3 2 3 3 3 3
> 9 I a tan(d x + c) + (- 6 I + 18 I)a tan(d x + c) + (6 I - 18 I)a
> d x
> /
> 6 d
> Type:
> Union(Expression(Integer),...)
> (3) -> D(eval(F, I =%i), x)-eval(f, I=%i)
>
> (3) 0
> Type:
> Expression(Complex(Integer))
> (4) -> F := integrate(eval(f, I=%i), x)
>
> >> System error:
> arithmetic error DIVISION-BY-ZERO signalled
> Operation was (/ -2 0).
>
> Any ideas?
This is old confusion between real and complex. We create
Complex(Complex(Integer)) and loose. It would be good to
clean this up. AFAICS proper fix should not require much
code, but it is going to touch several domains and packages.
Basically, old code assumed that functions are real and
allowed complex functions only as a hack. Current
'FunctionSpaceComplexIntegration' integrates _real_
function by passage to complex variables. We need a
function to integrate _complex_ functions.
--
Waldek Hebisch
--
You received this message because you are subscribed to the Google Groups
"FriCAS - computer algebra system" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to fricas-devel+unsubscr...@googlegroups.com.
To post to this group, send email to fricas-devel@googlegroups.com.
Visit this group at https://groups.google.com/group/fricas-devel.
For more options, visit https://groups.google.com/d/optout.
