one error in fminsearch?

Question

评论： Parham Babakhani Dehkordi 2015-3-31

I tried to use fminsearch to solve an equation with three unknown parameters but there is an error:

fi1=[0.6787*1.0e-5 0.4520*1.0e-5 0.3519*1.0e-5 0.2655*1.0e-5 0.2317*1.0e-5]; Hw=[0.3974 0.3186 0.2612 0.1816 0.1284];

The function is: error=fi1-(A+(B*(Hw^n))); I would like to compute A,B and n. Initial guess; A=0.005, B=0.4, n=2

The codes are but error say define B?

error=inline(fi1-(A+(B.*(Hw.^n)))); xo=[0.005 0.4 2]; [x,fval,exitflag,output] = fminsearch(error,x0)

Answer 1

Torsten 2015-3-31

error=@(x)(fi1-(x(1)+x(2)*Hw.^x(3)))*(fi1-(x(1)+x(2)*Hw.^x(3)))';
x0=[0.005 0.4 2];
[x,fval,exitflag,output] = fminsearch(error,x0);

Best wishes

Torsten.

Thank you Torsten, I copied your codes into my script, again there is an error as follows:

Attempt to execute SCRIPT fminsearch as a function: C:\Users\nima\Desktop\interfacial tensions\fminsearch.m

Error in interfacial_friction_factors (line 42) [x,fval,exitflag,output] = fminsearch(error,x0);