#8931: desolve
-------------------------+--------------------------------------------------
Reporter: descopau | Owner: burcin
Type: defect | Status: new
Priority: major | Milestone: sage-4.4.2
Component: symbolics | Keywords: desolve
Author: G.Connan | Upstream: N/A
Reviewer: | Merged:
Work_issues: |
-------------------------+--------------------------------------------------
I want to solve f''/f=k with k in R
{{{
sage: x=var('x')
sage: f=function('f',x)
sage: k=var('k')
sage: assume(k>0)
sage: desolve(diff(f(x),x,2)/f(x)==k,[f,x])
}}}
and sage keeps answering :
{{{
TypeError Traceback (most recent call
last)
/home/moi/<ipython console> in <module>()
/home/moi/sage-4.4.1-linux-32bit-
ubuntu_9.10-i686-Linux/local/lib/python2.6/site-
packages/sage/calculus/desolvers.pyc in desolve(de, dvar, ics, ivar,
show_method, contrib_ode)
338 # we produce string like this
339 # ode2('diff(y,x,2)+2*'diff(y,x,1)+y-cos(x),y(x),x)
--> 340 soln = maxima(cmd)
341
342 if str(soln).strip() == 'false':
/home/moi/sage-4.4.1-linux-32bit-
ubuntu_9.10-i686-Linux/local/lib/python2.6/site-
packages/sage/interfaces/expect.pyc in __call__(self, x, name)
1030
1031 if isinstance(x, basestring):
-> 1032 return cls(self, x, name=name)
1033 try:
1034 return self._coerce_from_special_method(x)
/home/moi/sage-4.4.1-linux-32bit-
ubuntu_9.10-i686-Linux/local/lib/python2.6/site-
packages/sage/interfaces/expect.pyc in __init__(self, parent, value,
is_name, name)
1449 except (TypeError, KeyboardInterrupt, RuntimeError,
ValueError), x:
1450 self._session_number = -1
-> 1451 raise TypeError, x
1452 self._session_number = parent._session_number
1453
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?
}}}
so I tried :
{{{
sage: desolve(diff(f(x),x,2)/f(x)==k^2+1,[f,x])
}}}
and I got :
{{{
k1*e^(I*sqrt(-k^2 - 1)*x) + k2*e^(-I*sqrt(-k^2 - 1)*x)
}}}
!!
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/8931>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
--
You received this message because you are subscribed to the Google Groups
"sage-trac" group.
To post to this group, send email to [email protected].
To unsubscribe from this group, send email to
[email protected].
For more options, visit this group at
http://groups.google.com/group/sage-trac?hl=en.
