MATLAB: Error using fminbnd function

fminbnd

i am trying to minimize function vDS_ using following commands

syms x

iC1_ = 1-3.58*sin(x+2.57)+0.86*cos(3*x)+1.227*sin(3*x)+2.17*sin(x+2.57) – 0.536;

f = int(iC1_,[0.75*pi x]);

VIN = int(f,[0.75*pi 2*pi]);

vDS_ = 2*pi*f/VIN;

fplot(vDS_,[0.75*pi,2*pi]);

[x,fval] = fminbnd(vDS_,0.75*pi,2*pi)

vDS_max = fval

But I am getting error as shown below

Error using fcnchk (line 106)

If FUN is a MATLAB object, it must have an feval method.

Error in fminbnd (line 191)

funfcn = fcnchk(funfcn,length(varargin));

Error in abc (line 7)

[x,fval] = fminbnd(vDS_,0.75*pi,2*pi)

Is there any problem with function definition?

Best Answer

Convert vDS_ via "matlabFunction" to a numerical function handle before calling "fminbnd".

Related Solutions

MATLAB: Fminsearch error regarding matrix dimensions

MiauMiau, the function funct has only one dependent variable, x, correct? If so this needs to be reflected in the function call for fminsearch

 [x,fval] = fminsearch(funct, 0);

With your function call

 [x,fval] = fminsearch(funct, [0, 10]);

you assign starting values for a 2-vector, e.g. x1 and x2.

MATLAB: Error using fminbnd function

Since you have created your objective function using symbolic variables, you need to convert them to function handles before you can use them to call FMINBND,

Try the following:

syms x;
f=sqrt(3-2*sqrt(x)); a=0; b=1;
dfdx2=-abs(diff(f,2));
dfdx4=-abs(diff(f,4));
F2 = matlabFunction(dfdx2)
F4 = matlabFunction(dfdx4)
M2=-fminbnd(F2,a,b);
M4=-fminbnd(F4,a,b);

Best Answer

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MATLAB: Fminsearch error regarding matrix dimensions

MATLAB: Error using fminbnd function

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