Why am I getting "Error in fmincon (line 497) xIndices = classifyBo​undsOnVars​(l,u,sizes​.nVar,true​);" when running fmincon

I am running a very simple code using matlab 2015b.

I create a simple function myfun as follows:

%------------------
function f = myfun(x)

f = f = (x(1)^2 + x(2)^2 + x(3)^2);

%-------------------

Then I have these two lines in a script:

x0 = [10;10;10]; 

[x,fval] = fmincon(@myfun,x0);

%-------------------

When I run this script, maltlab gives an error:

Undefined function or variable 'classifyBoundsOnVars'.

Error in fmincon (line 497)
    xIndices = classifyBoundsOnVars(l,u,sizes.nVar,true);

Many thanks for your help.

[Yuebin Zhou]

Use the following command and see if these functions are present on your computer.

>> which -all fmincon

>> which -all classifyBoundsOnVars

'fmincon' function does not come with base MATLAB but is in the Optimization toolbox, so please also check if you have this toolbox on your license.