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imageset(lambda x: x**2/(x**2 - 4), S.Reals) returns (1, ∞) #10113

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gxyd opened this Issue Nov 4, 2015 · 1 comment

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gxyd commented Nov 4, 2015

>>> f = x**2/(x**2 - 4)
>>> imageset(x, f, S.Reals)
(1, ∞)                 # this is wrong

>>> imageset(x, f, Interval(1, oo))
(-∞, -1/3] ∪ (1, ∞)                              # this is correct

Since [1, ∞).is_subset(S.Reals)

gxyd pushed a commit to gxyd/sympy that referenced this issue Nov 4, 2015

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gxyd commented Nov 15, 2015

Now i checked from google for its graph, which clearly shows that
range of x**2/(x**2 - 4) overs S.Reals should be (-∞, 0] ∪ (1, ∞).

skirpichev added a commit to skirpichev/diofant that referenced this issue Jul 16, 2016

imageset of first interval of singularities included
fixes sympy/sympy#10113

// edited by skirpichev

Signed-off-by: Sergey B Kirpichev <skirpichev@gmail.com>

skirpichev added a commit to skirpichev/diofant that referenced this issue Jul 17, 2016

imageset of first interval of singularities included
fixes sympy/sympy#10113

// edited by skirpichev

Signed-off-by: Sergey B Kirpichev <skirpichev@gmail.com>

skirpichev added a commit to skirpichev/diofant that referenced this issue Jul 17, 2016

imageset of first interval of singularities included
fixes sympy/sympy#10113

// edited by skirpichev

Signed-off-by: Sergey B Kirpichev <skirpichev@gmail.com>
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