Wrong factorization of expressions containing exponentials ?

asked 2019-02-15 13:40:40 +0100

updated 2023-01-09 23:59:49 +0100

tmonteil
27423 ●31 ●204 ●517 http://wiki.sagemath.o...

Is there something wrong with the factorization of expressions containing exponentials ? I obtain the following strange results (Sagemath 8.6):
factor(exp(-x)+2*exp(x)) ---> 3*e^x,
factor(exp(-x)+x*exp(-x)) ---> (x + 1)*e^x

Any suggestions welcomed.

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answered 2019-02-16 14:55:15 +0100

eric_g
8424 ●10 ●62 ●166 https://luth.obspm.fr/...

updated 2019-02-16 17:26:22 +0100

Thanks for the report. Looks like a terrible bug! It was introduced in SageMath 8.4: it is already there, while in SageMath 8.3, we get a mathematically correct result:

sage: factor(exp(-x)+2*exp(x))
(2*e^(2*x) + 1)*e^(-x)

I've opened the Trac ticket #27304 for it.

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Thanks a lot for the reply. The bug is also present in cocalc.

irizos ( 2019-02-16 15:15:17 +0100 )edit

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Asked: 2019-02-15 13:40:40 +0100

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Last updated: Feb 16 '19

Wrong factorization of expressions containing exponentials ? edit