How do i setup for this function?
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Kemal cevizli
on 24 Nov 2014
Answered: Roger Stafford
on 24 Nov 2014
I know this is pretty simple thing but I just started using matlab so don`t know how to set up variables for this one.
X=(0.5454*Mu+0.015*Kbf)/(Kbf-0.1818*Mu)
Y=((0.4545*Mu)+0.0155*(1-Kbf))/((1-Kbf)+(0.1818*Mu))
and X<Y
For Mu=0.2,0.4,0.6,0.8,
I need to find min Kbf value. How can I set this up?
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Roger Stafford
on 24 Nov 2014
If we call d = Y-X, by plotting d as a function of Kbf it is immediately evident that Kbf attains a minimum when d is zero. (Strictly speaking, if we require that Y>X, then Kbf cannot attain a minimum, so I will change your condition to Y>=X.) Setting d equal to 0, the resulting equation in Kbf can be converted (after some effort) to the following equivalent quadratic equation:
-0.0005*Kbf^2+(0.9849909*Mu+0.0155)*Kbf-0.72718182*Mu^2-0.0028179*Mu = 0
Calling its coefficients A, B, and C
A = -0.0005;
B = 0.9849909*Mu+0.0155;
C = -0.72718182*Mu^2-0.0028179*Mu;
the smaller of the two roots can be expressed as:
Kbf = -2*C/(B+sqrt(B^2-4*A*C));
which is the solution to your problem after you plug in the value of Mu.
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