# I am using bisection method to solve an equation, but the solution always shows the first value input and I don't know where my mistake is

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Mohamed T. Adam on 23 Dec 2021
Answered: Walter Roberson on 23 Dec 2021
I am using the biscetion method to solve an equation but the solution is always the first picked value (xLeft).
bisection_method()
Error as percentage: 0 friction factor: 0.008 Solution reached in 57 iterations
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### Answers (1)

Walter Roberson on 23 Dec 2021
D=0.1016; Q=0.00368; p=900;u=0.008; e=0;
A = (1/4)*pi*D^2;
R = (p*D*Q)/(u*A);
f = @(ft) 1/(-2*log((e/D)/3.7)+(2.51/(R*(ft^0.5))))^2;
syms ft
f(ft)
ans =
simplify(ans)
ans =
Notice the infinity, which is from the log((e/D)/3.7) when e is 0.
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