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Hila
01/04/13 2:44pm

I defined a function ProfitRetailSolo, and one of the parameters it takes is R.

I can not get closed form expressions for the value of R that maximizes ProfitRetailSolo. SO I am doing some numerical analysis.

As can be seen below I used Reduce and required the first deriviative to equal 0 and the second derivative to be negative.
With the specific values I am using for the other parameters- The output is that there are two values of R for which above holds: R == 73.1497 || R == 77.5785 (see below)


But when I then try to plug back above values in the derivative-- I dont get 0.
Also plotting the ProfitRetailSolo function, it does not have a maximum around R=73.
Can someone help me get correct result for the value of R that maximizes ProfitRetailSolo?

Thanks!
Hila

R1t = N[FullSimplify[
Reduce[{D[ProfitRetailSolo[80, 100, 0.8, 1.5, 0, R, 8], R] == 0,
D[ProfitRetailSolo[80, 100, 0.8, 1.5, 0, R, 8], {R, 2}] < 0,
R < 0.8 100, R > 0.8 80}, R]]]

Out[124]= R == 73.1497 || R == 77.5785

In[122]:= D[ProfitRetailSolo[80, 100, 0.8, 1.5, 0, R, 8], R]

Out[122]= -((
9.31323*10^-10 (-64. +
R)^7 (3.\[VeryThinSpace]+ (-1 +
2.32831*10^-10 (-64. + R)^8) (80.\[VeryThinSpace]+ R)))/(-1 +
2.32831*10^-10 (-64. + R)^8)^2) + (-1 +
2.32831*10^-10 (-64. + R)^8 +
1.86265*10^-9 (-64. + R)^7 (80.\[VeryThinSpace]+ R))/(
2 (-1 + 2.32831*10^-10 (-64. + R)^8))

In[123]:= N[% /. R -> 77.57851923357128`, 20]

Out[123]= 0.0549258

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Subject (listing for 'Numerical analysis gives wrong result')
Author Date Posted
Numerical analysis gives wrong result Hila 01/04/13 2:44pm
Re: Numerical analysis gives wrong result yehdua 01/05/13 2:07pm
Re: Numerical analysis gives wrong result yehuda 01/05/13 5:38pm
Re: Re: Numerical analysis gives wrong result Hila 01/06/13 09:14am
Re: Re: Re: Numerical analysis gives wrong result yehuda 01/08/13 07:45am
Re: Re: Re: Re: Numerical analysis gives wrong ... Hila 01/12/13 3:39pm
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