roots
- To: mathgroup at smc.vnet.net
- Subject: [mg29380] roots
- From: maarten.vanderburgt at icos.be
- Date: Sat, 16 Jun 2001 02:47:52 -0400 (EDT)
- Sender: owner-wri-mathgroup at wolfram.com
hallo,
What is the easiest solution to finding the 13 (real) roots of 0.05 x +
Cos[x] == 0.
I can be easily seen that there are 13 roots by plotting:
Plot[{0.05 x,-Cos[x]},{x,-30,30}]
but this is not sufficient for finding accurate numerical values.
FindRoot only gives one value and it is hard to predict which root it will find with a specified start value:
In[83]:= FindRoot[0.05 x +Cos[x] == 0,{x,0}]
Out[83]= {x -> -4.96317}
There are three roots closer to 0 then x == -4.96317
An NSolve only works for polynomials.
Is there no simple way to find all roots of such an equation, eventually within a specified range.
thanks for your help
Maarten van der Burgt
Leuven
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