Calling Octave package function from C++ code

[Shamika Mohanan]

I'm calling Octave package function from c++ code-

in = octave_value ('s');
octave_value_list out =feval ("tf", in, 1);

I get the following error-

warning: the 'tf' function belongs to the control package from Octave Forge which you have installed but not loaded. To load the package, run 'pkg load control' from the Octave prompt.
Please read <http://www.octave.org/missing.html> to learn how you can contribute missing functionality.

error: feval: function 'tf' not found

Is it possible to call Octave package functions from c++? Is there an equivalent for 'pkg load' that can be used in c++ code?

Shamika