Re: NMinimize Bug in Mathematica 7.0?
- To: mathgroup at smc.vnet.net
- Subject: [mg96248] Re: [mg96197] NMinimize Bug in Mathematica 7.0?
- From: Bob Hanlon <hanlonr at cox.net>
- Date: Tue, 10 Feb 2009 05:50:52 -0500 (EST)
- Reply-to: hanlonr at cox.net
poly = x^4 - 3 x^2 + x;
Plot[poly, {x, -2, 2}, PlotRange -> {-3.6, .5}]
NMinimize[poly, x]
{-1.07023,{x->1.1309}}
Use Minimize
Minimize[poly, x] // N
{-3.51391,{x->-1.30084}}
A constraint
NMinimize[{poly, x < 0}, x]
{-3.51391,{x->-1.30084}}
Or a starting interval
NMinimize[poly, {x, -2, 1}]
{-3.51391,{x->-1.30084}}
Bob Hanlon
---- appris at att.net wrote:
=============
Here is an example from Mathematica's user's guide:
In[8]:= NMinimize[x^4 - 3 x^2 + x, x]
Out[8]= {-3.513905039, {x -> -1.300839566}}
however, trying to replicate it, I get the following:
In[2]:= NMinimize[x^4 - 3 x^2 + x, x]
Out[2]= {-1.070230182, {x -> 1.130901122}}
One way to find the global min, I had to use a constraint such as x<0.
Has anyone come across such a problem?
In[3]:= $Version
Out[3]= "7.0 for Microsoft Windows (32-bit) (November 10, 2008)"
Thanks.