Error using fminbnd function

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?

Answer 1

[Torsten]

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

[HIMANSHU SHARMA]

Its working, thanks sir,

[Matt J]

@HIMANSHU,

You should Accept-click Torsten's answer, if it solved your difficulty.