id	summary	reporter	owner	description	type	status	priority	milestone	component	resolution	keywords	cc	work_issues	upstream	reviewer	author	merged	dependencies	stopgaps
9710	Assumptions not passed to differential equation solver	kedlaya	burcin	"The assume function doesn't seem to work with the differential equation solver, despite what the documentation for desolve suggests. This returns an error:
{{{
sage: x = var('x')
sage: k = var('k')
sage: y = function('y',x)
sage: assume(k>0)
sage: print desolve(diff(y,x,x)+k*y-exp(-k*x),[y,x])
Traceback (most recent call last):
  File ""<stdin>"", line 1, in <module>
  File ""_sage_input_25.py"", line 10, in <module>
    exec compile(u'open(""___code___.py"",""w"").write(""# -*- coding: utf-8 -*-\\n"" + _support_.preparse_worksheet_cell(base64.b64decode(""eCA9IHZhcigneCcpCmsgPSB2YXIoJ2snKQp5ID0gZnVuY3Rpb24oJ3knLHgpCmFzc3VtZShrPjApCnByaW50IGRlc29sdmUoZGlmZih5LHgseCkrayp5LWV4cCgtayp4KSxbeSx4XSk=""),globals())+""\\n""); execfile(os.path.abspath(""___code___.py""))
  File """", line 1, in <module>
    
  File ""/tmp/tmpyNFGr0/___code___.py"", line 7, in <module>
    exec compile(u'print desolve(diff(y,x,x)+k*y-exp(-k*x),[y,x])
  File """", line 1, in <module>
    
  File ""/home/kedlaya/sage-complete/local/lib/python2.6/site-packages/sage/calculus/desolvers.py"", line 340, in desolve
    soln = maxima(cmd)
  File ""/home/kedlaya/sage-complete/local/lib/python2.6/site-packages/sage/interfaces/expect.py"", line 1032, in __call__
    return cls(self, x, name=name)
  File ""/home/kedlaya/sage-complete/local/lib/python2.6/site-packages/sage/interfaces/expect.py"", line 1451, in __init__
    raise TypeError, x
TypeError: Computation failed since Maxima requested additional constraints (try the command 'assume(k>0)' before integral or limit evaluation, for example):
Is  k  positive, negative, or zero?
}}}
Found by Praveen N. and Aashita during Sage Days 25 coding sprint.
"	defect	closed	major	sage-duplicate/invalid/wontfix	calculus	duplicate	differential equations, assumptions	robert.marik kcrisman jdemeyer		N/A	Karl-Dieter Crisman