The following comes from my current `lts` branch:
>>> var('A:C')
(A, B, C)
>>> i = Piecewise((A, x<1), (B, x>2), (C, True)).integrate(x); i # new
continuous result
Piecewise((A*x, x <= 1), (A + C*x - C, x <= 2), (A + B*x - 2*B + C, True))
>>> for j in range(0,6):
... j,i.subs(x,j)
...
(0, 0)
(1, A)
(2, A + C)
(3, A + B + C)
(4, A + 2*B + C)
(5, A + 3*B + C)
>>> pwi = Piecewise((A, x<1), (B, x>2), (C, True)).piecewise_integrate(x) #
old discontinuous result
>>> pwi
Piecewise((A*x, x < 1), (B*x, x > 2), (C*x, True))
>>> for j in range(0,6):
... j,pwi.subs(x,j)
...
(0, 0)
(1, C)
(2, 2*C)
(3, 3*B)
(4, 4*B)
(5, 5*B)
The inequalities changing to equalities represents a corner case that I
haven't addressed yet. It especially shows up when the derivatives of the
integral are computed:
>>> i.diff(x)
Piecewise((A, x <= 1), (C, x <= 2), (B, True))
>>> pwi.diff(x)
Piecewise((A, x < 1), (B, x > 2), (C, True))
The reversal of args is correct in the first case: the args are ordered
according to spatial appearance along the x-axis.
On Wednesday, June 21, 2017 at 9:21:44 AM UTC-5, Aaron Meurer wrote:
>
> Can you give an example of old vs. new behavior? Are they mathematically
> equivalent (up to pievewise constant)?
>
> Aaron Meurer
>
> On Tue, Jun 20, 2017 at 8:37 AM Chris Smith <[email protected]
> <javascript:>> wrote:
>
>> Currently, indefinite integration of Piecewise gives the discontinuous
>> Piecewise result obtained by simply integrating the pieces of the
>> Piecewise. I propose (in PR #12587) that the `integrate` method give the
>> continuous result and a method `piecewise_integrate` be used to return the
>> old behavior. Are there other ideas? Do we need a deprecation of the old
>> behavior?
>>
>> --
>> You received this message because you are subscribed to the Google Groups
>> "sympy" group.
>> To unsubscribe from this group and stop receiving emails from it, send an
>> email to [email protected] <javascript:>.
>> To post to this group, send email to [email protected] <javascript:>
>> .
>> Visit this group at https://groups.google.com/group/sympy.
>> To view this discussion on the web visit
>> https://groups.google.com/d/msgid/sympy/95872e1e-ac0e-4b3d-b1c2-43520fa88158%40googlegroups.com
>>
>> <https://groups.google.com/d/msgid/sympy/95872e1e-ac0e-4b3d-b1c2-43520fa88158%40googlegroups.com?utm_medium=email&utm_source=footer>
>> .
>> For more options, visit https://groups.google.com/d/optout.
>>
>
--
You received this message because you are subscribed to the Google Groups
"sympy" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
To post to this group, send email to [email protected].
Visit this group at https://groups.google.com/group/sympy.
To view this discussion on the web visit
https://groups.google.com/d/msgid/sympy/23828d79-5a21-4961-9e84-977916751c64%40googlegroups.com.
For more options, visit https://groups.google.com/d/optout.
