InequalitySolve
- To: mathgroup at smc.vnet.net
- Subject: [mg37767] InequalitySolve
- From: "PSi" <no at eee.gr>
- Date: Tue, 12 Nov 2002 03:13:21 -0500 (EST)
- Sender: owner-wri-mathgroup at wolfram.com
In[1]:= << Algebra`InequalitySolve`
Example 1.
In[2]:= N[InequalitySolve[x^5 - x^3 - 1 == 0 && 0 < x < 2, x] ]
Out[2]:= x == 1.23651
Example 2.
In[3]:= NSolve[x^6 - x^3 - 1 == 0, x]
Out[3]:= {{x -> -0.8518}, {x -> -0.586992 - 1.0167 I},
{x -> -0.586992 + 1.0167 I }, {x -> 0.4259 - 0.73768 I},
{x -> 0.4259 + 0.73768 I}, {x -> 1.17398}}
In[4]:= N[InequalitySolve[x^6 - x^3 - 1 == 0 && 0 < x < 2, x] ]
Of course the answer should be x == 1.17398 as in the first example. Instead of
this, Mathematica 4.1 for Windows gives the following:
Greater::"nord" : "Invalid comparison with (-1)^(2/3)(1/2-Sqrt[5]/2)^(1/3)
attempted.
Less::"nord" : "Invalid comparison with -2+(-1)^(2/3)(1/2-Sqrt[5]/2)^(1/3)
attempted.
Out[4]:= x>0.&&x<2.&&x==-0.8518+3.88578*10^-16 I || x == 1.17398
Could anybody explain this?
Thanks
PSi