Problem with the Inverse CDF of Non-central F Ratio Distribution












2












$begingroup$


In[3]:= n = 5; n1 = 4; n2 = 6; γ = 0.05; α = 1/370;
InverseCDF[NoncentralFRatioDistribution[1, n1 - 1, n1/γ^2],
1 - α - (n - n1)/n2]



During evaluation of In[3]:= FindRoot::lstol: The line search
decreased the step size to within tolerance specified by AccuracyGoal
and PrecisionGoal but was unable to find a sufficient decrease in the
merit function. You may need more than MachinePrecision digits of
working precision to meet these tolerances. >>




Out[4]= 3.24659


The correct answer is 5468.146427955789










share|improve this question









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$endgroup$

















    2












    $begingroup$


    In[3]:= n = 5; n1 = 4; n2 = 6; γ = 0.05; α = 1/370;
    InverseCDF[NoncentralFRatioDistribution[1, n1 - 1, n1/γ^2],
    1 - α - (n - n1)/n2]



    During evaluation of In[3]:= FindRoot::lstol: The line search
    decreased the step size to within tolerance specified by AccuracyGoal
    and PrecisionGoal but was unable to find a sufficient decrease in the
    merit function. You may need more than MachinePrecision digits of
    working precision to meet these tolerances. >>




    Out[4]= 3.24659


    The correct answer is 5468.146427955789










    share|improve this question









    New contributor




    Abdul Haq is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
    Check out our Code of Conduct.







    $endgroup$















      2












      2








      2





      $begingroup$


      In[3]:= n = 5; n1 = 4; n2 = 6; γ = 0.05; α = 1/370;
      InverseCDF[NoncentralFRatioDistribution[1, n1 - 1, n1/γ^2],
      1 - α - (n - n1)/n2]



      During evaluation of In[3]:= FindRoot::lstol: The line search
      decreased the step size to within tolerance specified by AccuracyGoal
      and PrecisionGoal but was unable to find a sufficient decrease in the
      merit function. You may need more than MachinePrecision digits of
      working precision to meet these tolerances. >>




      Out[4]= 3.24659


      The correct answer is 5468.146427955789










      share|improve this question









      New contributor




      Abdul Haq is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.







      $endgroup$




      In[3]:= n = 5; n1 = 4; n2 = 6; γ = 0.05; α = 1/370;
      InverseCDF[NoncentralFRatioDistribution[1, n1 - 1, n1/γ^2],
      1 - α - (n - n1)/n2]



      During evaluation of In[3]:= FindRoot::lstol: The line search
      decreased the step size to within tolerance specified by AccuracyGoal
      and PrecisionGoal but was unable to find a sufficient decrease in the
      merit function. You may need more than MachinePrecision digits of
      working precision to meet these tolerances. >>




      Out[4]= 3.24659


      The correct answer is 5468.146427955789







      numerics probability-or-statistics accuracy-and-precision






      share|improve this question









      New contributor




      Abdul Haq is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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      share|improve this question









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      share|improve this question




      share|improve this question








      edited 1 hour ago









      gwr

      7,58822558




      7,58822558






      New contributor




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      asked 4 hours ago









      Abdul HaqAbdul Haq

      141




      141




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      New contributor





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          1 Answer
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          4












          $begingroup$

          Use FindRoot directly with arbitrary-precision



          n = 5; n1 = 4; n2 = 6; γ = 1/20; α = 1/370;

          icdf = x /.
          FindRoot[CDF[NoncentralFRatioDistribution[1, n1 - 1, n1/γ^2], x] ==
          1 - α - (n - n1)/n2, {x, 500},
          WorkingPrecision -> $MachinePrecision]

          (* 5468.146403807255 *)


          Verifying,



          (CDF[NoncentralFRatioDistribution[1, n1 - 1, n1/γ^2], icdf] // 
          RootApproximant) === 1 - α - (n - n1)/n2

          (* True *)


          Note that while the starting value used in FindRoot needs to be large, it does not have to be particularly close to the actual value.






          share|improve this answer









          $endgroup$













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            1 Answer
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            1 Answer
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            active

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            4












            $begingroup$

            Use FindRoot directly with arbitrary-precision



            n = 5; n1 = 4; n2 = 6; γ = 1/20; α = 1/370;

            icdf = x /.
            FindRoot[CDF[NoncentralFRatioDistribution[1, n1 - 1, n1/γ^2], x] ==
            1 - α - (n - n1)/n2, {x, 500},
            WorkingPrecision -> $MachinePrecision]

            (* 5468.146403807255 *)


            Verifying,



            (CDF[NoncentralFRatioDistribution[1, n1 - 1, n1/γ^2], icdf] // 
            RootApproximant) === 1 - α - (n - n1)/n2

            (* True *)


            Note that while the starting value used in FindRoot needs to be large, it does not have to be particularly close to the actual value.






            share|improve this answer









            $endgroup$


















              4












              $begingroup$

              Use FindRoot directly with arbitrary-precision



              n = 5; n1 = 4; n2 = 6; γ = 1/20; α = 1/370;

              icdf = x /.
              FindRoot[CDF[NoncentralFRatioDistribution[1, n1 - 1, n1/γ^2], x] ==
              1 - α - (n - n1)/n2, {x, 500},
              WorkingPrecision -> $MachinePrecision]

              (* 5468.146403807255 *)


              Verifying,



              (CDF[NoncentralFRatioDistribution[1, n1 - 1, n1/γ^2], icdf] // 
              RootApproximant) === 1 - α - (n - n1)/n2

              (* True *)


              Note that while the starting value used in FindRoot needs to be large, it does not have to be particularly close to the actual value.






              share|improve this answer









              $endgroup$
















                4












                4








                4





                $begingroup$

                Use FindRoot directly with arbitrary-precision



                n = 5; n1 = 4; n2 = 6; γ = 1/20; α = 1/370;

                icdf = x /.
                FindRoot[CDF[NoncentralFRatioDistribution[1, n1 - 1, n1/γ^2], x] ==
                1 - α - (n - n1)/n2, {x, 500},
                WorkingPrecision -> $MachinePrecision]

                (* 5468.146403807255 *)


                Verifying,



                (CDF[NoncentralFRatioDistribution[1, n1 - 1, n1/γ^2], icdf] // 
                RootApproximant) === 1 - α - (n - n1)/n2

                (* True *)


                Note that while the starting value used in FindRoot needs to be large, it does not have to be particularly close to the actual value.






                share|improve this answer









                $endgroup$



                Use FindRoot directly with arbitrary-precision



                n = 5; n1 = 4; n2 = 6; γ = 1/20; α = 1/370;

                icdf = x /.
                FindRoot[CDF[NoncentralFRatioDistribution[1, n1 - 1, n1/γ^2], x] ==
                1 - α - (n - n1)/n2, {x, 500},
                WorkingPrecision -> $MachinePrecision]

                (* 5468.146403807255 *)


                Verifying,



                (CDF[NoncentralFRatioDistribution[1, n1 - 1, n1/γ^2], icdf] // 
                RootApproximant) === 1 - α - (n - n1)/n2

                (* True *)


                Note that while the starting value used in FindRoot needs to be large, it does not have to be particularly close to the actual value.







                share|improve this answer












                share|improve this answer



                share|improve this answer










                answered 1 hour ago









                Bob HanlonBob Hanlon

                59.2k33595




                59.2k33595






















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