Try mnewton,
%o12;
1000000 t
---------
33
297 E - 330
(%o26) t = --------------------
10000000
(%i27) mnewton([first(%o12) - second(%o12)],[t],[0]);
(%o27) [[t = - 1.2924737663022043E-5]]
(%i28)
-sen
On Thu, 30 Nov 2006, Daniel Lakeland wrote:
> On Thu, Nov 30, 2006 at 09:42:17PM +0100, Hugo Coolens wrote:
>> Is find_root a separate package? Where can I find it?
>>
>> I'll try it out on my system and tell you what the result is
>
> find_root is standard as of fairly recently. It used to be called
> "interpolate" but that was deemed confusing so it was renamed about a
> year ago I think. It's in the docs. It does a binary search followed
> by newton's method when it gets close enough.
>
> However, it seems to have a bug of sorts. Does anyone else see the
> behavior that I see? I confirmed it at home on linux as well as on
> windows at work.
>
> -----Transcript------
>
> Maxima 5.10.0 http://maxima.sourceforge.net
> Using Lisp GNU Common Lisp (GCL) GCL 2.6.7 (aka GCL)
>
>
> (%i1) h1(s):=1/(1+tau[1]*s);
> h2(s):=1/(1+tau[2]*s);
> x(s):=1/s;
> tau[1]:33e-6;
> tau[2]:33e-6;
> eqn:first(solve(ilt(h1(s)*h2(s)*x(s),s,t)=0.1,t));
> 1
> (%o1) h1(s) := ----------
> 1 + tau s
> 1
> (%i2) 1
> (%o2) h2(s) := ----------
> 1 + tau s
> 2
> (%i3) 1
> (%o3) x(s) := -
> s
> (%i4) (%o4) 3.2999999999999996E-5
> (%i5) (%o5) 3.2999999999999996E-5
> (%i6)
> `rat' replaced 3.2999999999999996E-5 by 33//1000000 = 3.3000000000000003E-5
>
> `rat' replaced 0.9 by 9//10 = 0.9
> 1000000 t
> ---------
> 33
> 297 %e - 330
> (%o6) t = ---------------------
> 10000000
> (%i7) find_root(%,t,0,2);
>
> Maxima encountered a Lisp error:
>
> Error in MACSYMA-TOP-LEVEL [or a callee]: ((MEQUAL SIMP) $T
> ((MTIMES SIMP)
> ((RAT SIMP) 1 10000000)
> ((MPLUS SIMP) -330
> ((MTIMES SIMP) 297
> ((MEXPT SIMP) $%E
> ((MTIMES SIMP)
> ((RAT SIMP) 1000000
> 33)
> $T)))))) is not of type (OR
> RATIONAL
> LISP:FLOAT).
>
> Automatically continuing.
> To reenable the Lisp debugger set *debugger-hook* to nil.
> (%i8)
>
>
--
---------------------------------------------------------------------------
| Sheldon E. Newhouse | e-mail: sen1 at math.msu.edu |
| Mathematics Department | |
| Michigan State University | telephone: 517-355-9684 |
| E. Lansing, MI 48824-1027 USA | FAX: 517-432-1562 |
---------------------------------------------------------------------------