Hello,
I have got some problems with equation :
f''/f=k
with k a real.
First, I can't divide a given equation by f(x)*g(t).
Beside, assume(k>0) seems not to be assumed by sage...
----------------------------------------------------------------------
| Sage Version 4.3.3, Release Date: 2010-02-21 |
| Type notebook() for the GUI, and license() for information. |
----------------------------------------------------------------------
sage: sage: var('x,t')
(x, t)
sage: z=function('z',x,t)
sage: f=function('f',x)
sage: g=function('g',t)
sage: z=f*g
sage: eq=(diff(z,x,2)==diff(z,t))
sage: eq
g(t)*D[0, 0](f)(x) == f(x)*D[0](g)(t)
sage: eq=(eq/(f(x)*g(t)))
/home/moi/sage-4.3.3-linux-32bit-ubuntu_9.10-i686-Linux/local/lib/
python2.6/site-packages/IPython/iplib.py:2073: DeprecationWarning:
Substitution using function-call syntax and unnamed arguments is
deprecated and will be removed from a future release of Sage; you can
use named arguments instead, like EXPR(x=..., y=...)
exec code_obj in self.user_global_ns, self.user_ns
sage: eq
D[0, 0](f)(x)/f(x) == D[0](g)(t)/g(t)
sage: k=var('k')
sage: assume(k>0)
sage: eq1=(eq.lhs()==k)
sage: f(t)=desolve(eq1,[f,x])
---------------------------------------------------------------------------
TypeError Traceback (most recent call
last)
/home/moi/<ipython console> in <module>()
/home/moi/sage-4.3.3-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-4.3.3-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-4.3.3-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?
sage:
--
Guillaume
--
To post to this group, send email to sage-support@googlegroups.com
To unsubscribe from this group, send email to
sage-support+unsubscr...@googlegroups.com
For more options, visit this group at
http://groups.google.com/group/sage-support
URL: http://www.sagemath.org
