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Wrong factorization of expressions containing exponentials ?

asked 2019-02-15 13:40:40 +0200

updated 2019-02-16 19:41:25 +0200

slelievre gravatar image

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 +0200

eric_g gravatar image

updated 2019-02-16 17:26:22 +0200

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 gravatar imageirizos ( 2019-02-16 15:15:17 +0200 )edit

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Asked: 2019-02-15 13:40:40 +0200

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Last updated: Feb 16 '19