Re: FindRoot for the determinant of a matrix with a varying size
- To: mathgroup at smc.vnet.net
- Subject: [mg59728] Re: FindRoot for the determinant of a matrix with a varying size
- From: "Jens-Peer Kuska" <kuska at informatik.uni-leipzig.de>
- Date: Fri, 19 Aug 2005 04:31:50 -0400 (EDT)
- Organization: Uni Leipzig
- References: <de13n4$8so$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Hi,
Clear[f]
f[x_?NumericQ] := Det[Table[Exp[(i - j)/x]/x , {i,
2, 5, x}, {j, 2, 5, x}]]
FindRoot[f[x] == 0.1, {x, 1, 5}]
Regards
Jens
"Wonseok Shin" <wssaca at gmail.com> schrieb im
Newsbeitrag news:de13n4$8so$1 at smc.vnet.net...
| Hello everyone,
|
| I am a user of Mathematica 5.1 for Mac .
| I defined the function using the determinant of
a matrix of a varying
| size. Even though this function is
well-behaving, it seems that
| FindRoot cannot deal this function. Please look
at the following code:
|
| -------------------------------------------------
| In[1]:=
| f[x_] := Det[Table[Exp[(i - j)/x]/x , {i, 2, 5,
x}, {j, 2, 5, x}]]
|
| In[2]:=
| Plot[f[x], {x, 3, 30}]
| -------------------------------------------------
|
| By running the above Plot command, you can see
clearly that the
| function f is very smooth in the interval 3< x <
30, and f[x] == 0.1
| has a solution in 5 < x < 15.
|
| But I've failed to find a solution of f[x] ==
0.1 using FindRoot:
|
| -------------------------------------------------
| In[3]:=
| FindRoot[f[x] == 0.1, {x, 5}]
|
| Table::iterb : Iterator {i, 2, 5, x} does not
have appropriate bounds.
| -------------------------------------------------
|
| Is there any workaround for this problem?
|
| Thanks,
|
| Wonseok Shin
|