Opened 2 years ago

Last modified 2 years ago

#26490 new defect

desolve issue when using symbolic constants in the initial conditions

Reported by: tmonteil Owned by:
Priority: major Milestone: sage-8.4
Component: symbolics Keywords:
Cc: Merged in:
Authors: Reviewers:
Report Upstream: N/A Work issues:
Branch: Commit:
Dependencies: Stopgaps:

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Description (last modified by tmonteil)

As reported on this ask question:

var('t') 
y = function('y')(t)
de1 = t^3*diff(y, t) + 4*t^2*y == e^(t^2)
desolve(de1, y, ics = [1,e])

leads to

1/2*(e^(t^2) + y(t))/t^4

Which is incorrect. The correct answer is:

1/2*(e + e^(t^2))/t^4

which can be obtained when replacing the symbolic constant e with the wymbolic expression e*1 in the initial conditions:

desolve(de1, y, ics = [1,e*1])

This seems to be caused by #26492.

Change History (2)

comment:1 Changed 2 years ago by tmonteil

  • Description modified (diff)

comment:2 Changed 2 years ago by mantepse

not really helpful, I guess, but

sage: desolve(de1, y, ics = [1,e], algorithm="fricas")
1/2*(e + e^(t^2))/t^4

works...

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