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[MUG] Bug VectorCalculus[Jacobian]
| [MUG] Bug VectorCalculus[Jacobian] |
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Author: Jarausch
Posted: Thu, 17 Oct 2002 19:44:11 +0200
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>> From: "jarausch"
Maple8 does not compute a Jacobian of a mapping of an
m-dimensional space into an n-dimensional one with
m different from n, although this is mathematically
well defined.
> with(LinearAlgebra):
> fp:=Vector(2,[p[1]*p[2],3*p[3]]);
[p[1] p[2]]
fp := [ ]
[ 3 p[3] ]
> VectorCalculus[Jacobian](fp,[p[1],p[2]]);
[p[2] p[1]]
[ ]
[ 0 0 ]
with assumptions on p
> VectorCalculus[Jacobian](fp,[p[1],p[2],p[3]]);
Error, (in VectorCalculus:-Jacobian) the number of functions must
equal the number of variable names
Is there any workaround?
Thanks for a hint,
Helmut Jarausch
Lehrstuhl fuer Numerische Mathematik
Institute of Technology, RWTH Aachen
D 52056 Aachen, Germany
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| [MUG] Re: Bug VectorCalculus[Jacobian] |
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Author: Maple User Group
Posted: Tue, 22 Oct 2002 11:43:05 -0400
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>> From: Maple User Group "maple_gr"
On Thu, 17 Oct 2002 "jarausch" wrote:
|> Maple8 does not compute a Jacobian of a mapping of an
|> m-dimensional space into an n-dimensional one with
|> m different from n, although this is mathematically
|> well defined.
|> > VectorCalculus[Jacobian](fp,[p[1],p[2],p[3]]);
|> Error, (in VectorCalculus:-Jacobian) the number of functions must
|> equal the number of variable names
|> Is there any workaround?
-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-
Date: Sun, 20 Oct 2002 12:46:36 -0700 (PDT)
From: Robert Israel "israel"
To: "maple-list"
Subject: Bug VectorCalculus[Jacobian]
Well, you could simply roll your own:
> MyJacobian:= (F::list, V::list) ->
Matrix([seq([seq(diff(f,v),v=V)], f=F)]);
Or patch VectorCalculus:-Jacobian to remove the line
if lenf <> lenv then error "the number of functions must equal the number
of variable names" end if;
(although there should still be an error if you ask it to compute the
determinant in this case)
Robert Israel "israel"
Department of Mathematics http://www.math.ubc.ca/~israel
University of British Columbia
Vancouver, BC, Canada V6T 1Z2
-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-
Date: Sun, 20 Oct 2002 19:39:30 -0400 (EDT)
From: Carl Devore "devore"
To: "maple-list"
Subject: Bug VectorCalculus[Jacobian]
Yes, this is an oversight. In the small procedure
VectorCalculuc:-Jacobian, the line
if lenf <> lenv then
should be changed to
if computedet and lenf <> lenv then
> Is there any workaround?
Yes,
Matrix(linalg[jacobian](fp, [p[1], p[2], p[3]]));
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