MATLAB: Problem related to fminbnd

fminbnd

I am finding the minimum value of Lr in the non-linear function. but whatever value of constants I change there is no effect on the minimum value. Also the minimum value I am getting is not correct.
fun=@(Lr)(((Vin*Cr*Lm)/(((((Z*Cc)+((A+(B*Cr))*((B*Cr)+C)*Lr))/Cc)+((ilm*ilm*Lm*Cc)/(((Z*Cc)+((A+(B*Cr))*((B*Cr)+C)*Lr))/Cc)))*(((1-D)*Ts)-((ilm*Lm)/(((Z*Cc)+((A+(B*Cr))*((B*Cr)+C)*Lr))/Cc)))))+((Lr*(((((Z*Cc)+((A+(B*Cr))*((B*Cr)+C)*Lr))/Cc)+((ilm*ilm*Lm*Cc)/(((Z*Cc)+((A+(B*Cr))*((B*Cr)+C)*Lr))/Cc)))*(((1-D)*Ts)-((ilm*Lm)/(((Z*Cc)+((A+(B*Cr))*((B*Cr)+C)*Lr))/Cc)))))/(Lm*Vin))+((C*Lr)/Vin));
[Lr,fval] = fmincon(fun,0,10e-6)
where all other variables are constants and their resp. values are given

Best Answer

You could plot the function to see how its shape varies with the parameters and to confirm whether fminbnd is giving the correct result.