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Re: Solving the system with inexact coefficients

• To: mathgroup at smc.vnet.net
• Subject: [mg99383] Re: [mg99335] Solving the system with inexact coefficients
• From: "David Park" <djmpark at comcast.net>
• Date: Mon, 4 May 2009 06:02:07 -0400 (EDT)
• References: <30708295.1241344271268.JavaMail.root@n11>

It looks like something you have to use FindRoot on. Or better yet Ted
Ersek's RootSearch package from MathSource at the WRI site. (With changes in
7.0.1 RootSearch now gives a warning message that can usually be ignored. It
is too bad because RootSearch is much better than FindRoot for root
searching in 1-dimension.)


David Park
djmpark at comcast.net
http://home.comcast.net/~djmpark/  



From: Desana [mailto:incolaster at gmail.com] 


Hello,
this is my problem : I've got cca 40 sinusoidal waves ( e.g. 0.118149
Cos[25.1013 t]) and after superposition I get irregurar wave record.
I'm trying to see how many waves I have in certain interval by finding
how many zero crossings there are:

Reduce[Total[Subscript[\[Eta], i]] == 0 && 0 < t < 60, t]

but I couldn't because "Reduce was unable to solve the system with
inexact coefficients"

What's the problem?  What does it mean?
Can I find intersection between my wave and x-axis in any other wave?
Perhaps graphically ?

Thank you,
student Desana