Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

cancel consistently handles exprs #12786

Closed
wants to merge 22 commits into from
Closed

cancel consistently handles exprs #12786

wants to merge 22 commits into from

Conversation

smichr
Copy link
Member

@smichr smichr commented Jun 22, 2017 •
edited 

>>> cancel((Poly(x),Poly(y)))
(1, Poly(x, x, y, domain='ZZ'), Poly(y, x, y, domain='ZZ'))
>>> cancel((Poly(x),Poly(y)), tuple=False)
x/y
>>> cancel(x/2+1)
(x + 2)/2
>>> cancel(x/2+1, tuple=True)
(1/2, x + 2, 1)
  • when the output is not a tuple, it will always be a fraction or an expression with numerator of 1,
    unevaluate if necessary
  • passing a tuple of length other than 2 is disabled
  • the handling of expressions and numerator/denominator tuples is separated

closes #12787
closes #11506

@smichr smichr changed the title cancel recognizes non-symbol gens cancel recognizes non-symbol gens and consistently handles exprs Jun 22, 2017
@smichr smichr force-pushed the cancel branch 5 times, most recently from 7b02128 to 897805a Compare June 25, 2017 03:47
@smichr smichr changed the title cancel recognizes non-symbol gens and consistently handles exprs cancel consistently handles exprs Jun 25, 2017
smichr
smichr commented Jun 27, 2017
View reviewed changes
sympy/polys/polytools.py Outdated
p, q = F
rv = c, n, d = _cancel_pq(p, q, *gens, **args)
if not as_tuple:
rv = _keep_coeff(c, nd)
Copy link
Member Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

nd->n, d and test this

smichr added 21 commits July 3, 2017 21:25
@smichr
cancel recognizes non-symbol gens
4f9f134 
The generators are recognized in the order given.

The return type is now consistently a Tuple.
@smichr
cancel processes only Add and Mul arguments
85b237f
@smichr
separate tuple and expr handling
e620a5e
@smichr
tuple in tuple out
209f548
@smichr
return p/q if polificaiton fails; flatten gens
f4695de
@smichr
reject non-Expr args encountered recursively
ba1df83
@smichr
use replace instead of preorder_traversal
c8b990e
@smichr
process args of noncommutative non-Mul, non-Add
d1af8a4
@smichr
use expansion in calculate_series
31e78bb 
A conequence of being consistent is that an expression like this:

exp(1 + log(_p)/_p)

formerly returned as this

E*exp(log(_p)/_p)

but now comes back as this:

exp((_p + log(_p))/_p)

The latter result is consistent with how the original cancel
gave cancel(exp(1 + x/y)) -> exp((y + x)/y).

Because of this change, expansion is now used in calculate_series.

A consequence of the expansion is that a former test that gave
sign(y)*I*oo now gives y*I*oo ... and that seems ok. The expanded
t in calculate_series for gruntz(y*3*sin(I)*x, x, oo) is now

-3*I*y*exp(-1)/(2*_w) +3*E*I*y/(2*_w)

while it was formerly

(-3*I*y + 3*I*y*exp(2))*exp(-1)/(2*_w)
@smichr
cancel processes iterable args, even non-Basic
7002885
@smichr
extract igcd; keep coeff; allow tuple result
e4cee67
@smichr
Piecewise.is_commutative is False for non-Basic args
c0b7147
@smichr
use only fraction for returning n, d
34f4be8
@smichr
import reduce; fix 11506 test
add291b
@smichr
remove non-symbol masking
29b6b7e
@smichr
leave coeffs distributed
4b9a00f
@smichr
include None results with nc
2332c5f
@smichr
typo
f33b831
@smichr
_unevaluated_Mul watches for nc args
b5aa24a
@smichr
_keep_coeff distinguishes btwn 1 and 1.0
785a35f
@smichr
cancel modifications and test updates
f5cbfec
@smichr smichr closed this Dec 10, 2017
@smichr smichr deleted the cancel branch September 12, 2018 17:46
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Reviewers
No reviews
Assignees
No one assigned
Labels
None yet
Projects
None yet
Milestone
No milestone
Development

Successfully merging this pull request may close these issues.

cancel should recognize non-Symbol generators cancel on expressions with exponentials
1 participant
@smichr