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Student Support Forum: 'Numerical analysis gives wrong result' topicStudent Support Forum > General > Archives > "Numerical analysis gives wrong result"

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Author Comment/Response
yehuda
01/05/13 5:38pm

I took few more minutes to look at your post
there is enough information there to look at
1. You mix exact numbers (integers) with machine precision numbers. One way to get more accurate results is to use rationals or determine the precision of the estimated numbers yourself
2. Using FindRoot is both fast and accurate
d1 = -((9.31323*10^-10 (-64. +
R)^7 (3. + (-1 + 2.32831*10^-10 (-64. + R)^8) (80. +
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. + R))/(2 (-1 +
2.32831*10^-10 (-64. + R)^8));
d2=D[d1,R];
sol=FindRoot[d1==0,{R,70,64,80}]
returns
{R -> 77.6988}
so
{d1,d2}/.sol
returning
{0., -0.492557}
meets your requirements
yehuda

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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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