FindRoot
- To: mathgroup at smc.vnet.net
- Subject: [mg70356] FindRoot
- From: dimmechan at yahoo.com
- Date: Sat, 14 Oct 2006 03:06:53 -0400 (EDT)
Hello. Let me deal with something elementary but yet confusing for me. Consider the equation cos(x)=x. FindRoot[Cos[x] == x, {x, 5}] {x -> 0.7390851332151607} This prints the value of x every time a step is taken. FindRoot[Cos[x] == x, {x, 5}, StepMonitor :> Print[x]] This gives a list of the steps taken. Reap[FindRoot[Cos[x] == x, {x, 5}, StepMonitor :> Sow[x]]] {{x -> 0.7390851332151607}, {{-1., -0.02837830412204312, 1.0296174587519653, 0.7525886779802748, 0.7391248287000711, 0.7390851335630761, 0.7390851332151607}}} This counts the steps. Block[{st = 0}, {FindRoot[Cos[x] == x, {x, 5}, StepMonitor :> st++], st}] {{x -> 0.7390851332151607}, 7} I want to know what exactly the following command gives. Reap[FindRoot[Cos[x] == x, {x, 5}, EvaluationMonitor :> Sow[x]]] {{x -> 0.7390851332151607}, {{5., -54.99999999999999, -1., 8.716216958779569, -0.02837830412204312, 1.0296174587519653, 0.7525886779802748, 0.7391248287000711, 0.7390851335630761, 0.7390851332151607}}} In versions earlier than 5.0 you could use the following command FindRoot[Print[x]; Cos[x] == x, {x, 5}] Why it cannot be used now? Thanks in advance for any help.
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