Re: ?
- To: mathgroup at smc.vnet.net
- Subject: [mg120816] Re: ?
- From: Murray Eisenberg <murray at math.umass.edu>
- Date: Thu, 11 Aug 2011 05:13:27 -0400 (EDT)
- Delivered-to: l-mathgroup@mail-archive0.wolfram.com
- References: <201108101047.GAA26230@smc.vnet.net>
- Reply-to: murray at math.umass.edu
This is something that arises even from plain Solve as well as DSolve, etc.: you get rules instead of values. Given a rule x -> val, the typical way you get the value val is: x /. x -> val This in your case either directly... x /. FindRoot[x+9,{x,-5}] ... or else in two steps: FindRoot[x+9,{x,-5}] x /. % Note that for things like Solve where multiple solutions are possible, the result of the x /. rule expression will be a list of the solutions. For example: x /. Solve[x^2 + 4 == 0, x] {-2I, 2I} On 8/10/11 6:47 AM, David Kirkby wrote: > The output of FindRoot[] when trying to find a root is like: > > {x -> 0.49454545} > > How can I convert that list, into the number 0.49454545? > > In[1]:= FindRoot[x+9,{x,-5}] > > Out[1]= {x -> -9.} > > In[2]:= Head[%] > > Out[2]= List > > I can't seem to find any "normal" operations on the list which give me > the number. > > Dave > -- Murray Eisenberg murray at math.umass.edu Mathematics & Statistics Dept. Lederle Graduate Research Tower phone 413 549-1020 (H) University of Massachusetts 413 545-2859 (W) 710 North Pleasant Street fax 413 545-1801 Amherst, MA 01003-9305
- References:
- How do I get a numeric value from FindRoot[] ?
- From: David Kirkby <david.kirkby@onetel.net>
- How do I get a numeric value from FindRoot[] ?