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Re: Multiple FindRoot

• To: mathgroup at smc.vnet.net
• Subject: [mg109828] Re: Multiple FindRoot
• From: "David Park" <djmpark at comcast.net>
• Date: Wed, 19 May 2010 07:03:58 -0400 (EDT)

You might try Ted Ersek's RootSearch package from WRI MathSource. It is much
more convenient than FindRoot for such cases.


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



From: EF [mailto:he.frauendorfer at t-online.de] 


Find Lambda Values for Tan[Lambda] == -([Lambda]/h) and e.g. h = 0.5

the first 10 Lambda Values for h = 0.5 are

In[27]:=Lambda =

Out[27]= {1.837, 4.816, 7.917, 11.04, 14.17, 17.31, 20.44, 23.58, 26.72, 
29.86}

My solution requires
1)  FindRoot for a wide range of starting (ending) values
2)  Eliminate the great number of double real solutions
3)  Verify solutions, there are "some" wrong values

Is there a more direct way to the correct lambda values?


E.F.