RE: no results with 'InequalitySolve'
- To: mathgroup at smc.vnet.net
- Subject: [mg42345] RE: [mg42334] no results with 'InequalitySolve'
- From: "Florian Jaccard" <jaccardf at eicn.ch>
- Date: Wed, 2 Jul 2003 06:36:07 -0400 (EDT)
- Sender: owner-wri-mathgroup at wolfram.com
First, you have to load a package :
<Algebra`InequalitySolve`
Then, it would be good to reed what this function does :
InequalitySolve[expr,x] : "find all real values of x that satisfy the
expression containing logical connectives and univariate polynomial
equations
and inequalities"
As you don't have a polynomial equation, it will not be very good !
In fact, you should better look in a drawing (for example :
Plot[{Sin[x],.5},{x,-10,10}] ) and you will see that you have a lot of
intervals that match your inequation.
Solve sin(x)=1/2 by hand (don't forget the + k*2Pi) and compare with the
drawing !
I you really want numerical intervals obtained by Mathematica, use a
Mc-Laurin developpement of your function ! But as sin(x) is periodic, I'm
not sure it is a good idea, because you will obtain only a small part of the
infinit number of possible intervals !
For example :
In[129]:=
Drop[Drop[InequalitySolve[Normal[Series[Sin[x], {x, 0, 100}]] > 0.5, x],
1], -1]
Out[129]=
-42.99449692883901 < x < -39.83527386680872 || -35.91239940014124 < x
< -35.552988467690014 ||
-30.890198125910032 < x < -28.798192964342267 || -24.609139496957557 < x
< -22.514747609756625 ||
-18.325957146022787 < x < -16.231562043257757 || -12.042771838770655 < x
< -9.948376736366814 ||
-5.759586531581283 < x < -3.665191429188094 || 0.5235987755982989 < x <
2.6179938779914944 ||
6.806784082777885 < x < 8.901179185170982 || 13.08996938997807 < x <
15.18436449221403 ||
19.373154695265853 < x < 21.467549856162726 || 25.656332591107713 < x <
27.750804666804388
Es scheint es gehe um Hausaufgaben ? Ich glaube, diese Erklärungen werden
genügen...
At work, now !
Florian Jaccard
professeur de Mathématiques
-----Message d'origine-----
De : Oliver Kowalke [mailto:oliver.kowalke at t-online.de]
Envoyé : mar., 1. juillet 2003 14:46
À : mathgroup at smc.vnet.net
Objet : [mg42334] no results with 'InequalitySolve'
Hi,
I've Mathematica 4.1 on Linux. If I try to solve this:
InequalitySolve[Sin[x] > 0.5, x]
Mathematica recalls it without solving it. Why? What do I've to do?
thx,
Oliver