Mathematica 9 is now available
Services & Resources / Wolfram Forums / MathGroup Archive
-----

MathGroup Archive 2013

[Date Index] [Thread Index] [Author Index]

Search the Archive

Re: FindRoot

  • To: mathgroup at smc.vnet.net
  • Subject: [mg131651] Re: FindRoot
  • From: Bob Hanlon <hanlonr357 at gmail.com>
  • Date: Sun, 15 Sep 2013 07:10:07 -0400 (EDT)
  • Delivered-to: l-mathgroup@mail-archive0.wolfram.com
  • Delivered-to: l-mathgroup@wolfram.com
  • Delivered-to: mathgroup-outx@smc.vnet.net
  • Delivered-to: mathgroup-newsendx@smc.vnet.net
  • References: <20130914100359.B62286A32@smc.vnet.net>

In Part I, n -- as defined in the module -- is given a transient value by
the expression

n /. FindRoot[powerEST - (1 - \[Beta]), {n, 40}]

Use Print statements to track what occurs.

f[n_, p1_, p2_] :=
  Sqrt[2 n] (ArcSin@Sqrt[p1 - 1/(2 n)] -
     ArcSin@Sqrt[p2 + 1/(2 n)]);

myModule1[=E1_, =E2_] := Module[{
    A = ConstantArray["", {9, 9}], n, powerEST,
    p1 = 0.2, p2 = 0.1, index1, index2, val},
   aIf[p1 > p2,
    powerEST = SurvivalFunction[
      NormalDistribution[f[n, 0.2, 0.1], 1],
      Quantile[NormalDistribution[], 1 - =E1]];
    Print["array indices = ",
     {index1 = IntegerPart[10 (p1 - 0.1)],
      index2 = IntegerPart[10 p2]}];
    Print[
     val =
      Ceiling[
       n /.
        FindRoot[powerEST - (1 - =E2), {n, 40},
         EvaluationMonitor :> Print["n = ", n]]]]];
   Print["But n was not set: n = ", n];
   A[[index1, index2]] = val];

myModule1[0.05,0.05]

array indices = {1,1}
n = 40.
n = 154.16
n = 226.772
n = 271.381
n = 287.216
n = 288.886
n = 288.903
n = 288.903
289
But n was not set: n = n$339
289


Bob Hanlon



On Sat, Sep 14, 2013 at 6:03 AM, <bruce.colletti at gmail.com> wrote:

> Re 9.0.1 under Windows 7.
>
> The code below is extracted from another source.
>
> Part I below returns 289 even though n is never given a value.  Why does
> the module return a value and in particular, what does 289 mean?
>
> Part II doesn't return a value (as expected).  I don't see why Part I
> returns a value but not Part II.
>
> Thanks.
>
> Bruce
>
>
> In[1]:=
> (* Part I *)
> f[n_,p1_,p2_]:=Sqrt[2n](ArcSin@Sqrt[p1-1/(2n)]-ArcSin@Sqrt[p2+1/(2n)]);
>
>
> myModule1[\[Alpha]_,\[Beta]_]:=Module[{A=ConstantArray["",{9,9}],n,po=
werEST,p1=0.2,p2=0.1},
> If[
> p1>p2,
>
> powerEST=SurvivalFunction[NormalDistribution[f[n,0.2,0.1],1],Quantile[N=
ormalDistribution[],1-\[Alpha]]];
>
>
> A[[IntegerPart[10(p1-0.1)],IntegerPart[10p2]]]=Ceiling[n/.FindRoot[powe=
rEST-(1-\[Beta]),{n,40}]]
> ]
> ];
>
> myModule1[0.05,0.05]
> Out[3]= 289
> In[4]:=
> (* Part II *)
> myModule2[\[Alpha]_,\[Beta]_]:=Module[{A=ConstantArray["",{9,9}],n},
>
> SurvivalFunction[NormalDistribution[f[n,0.2,0.1],1],Quantile[NormalDistri=
bution[],1-\[Alpha]]]
> ];
>
> myModule2[0.05,0.05]
> Out[5]= 1/2 Erfc[(1.64485 -Sqrt[2] Sqrt[n$272] (ArcSin[Sqrt[0.2 -1/(2
> n$272)]]-ArcSin[Sqrt[0.1 +1/(2 n$272)]]))/Sqrt[2]]
>
>




  • References:
    • FindRoot
      • From: bruce.colletti@gmail.com
  • Prev by Date: Re: multiintegral and table
  • Next by Date: Re: multiintegral and table
  • Previous by thread: FindRoot
  • Next by thread: Re: FindRoot