boost error: expression cannot be used as a function - c++

Question

I am trying to use the boost RK4 integration together with the rigid body dynamics library.
I am getting a strange error I dont recognize, that I think has to do with the operator() override but I am not sure based on this post.
My code is similar to this example. Which makes me think that either I am missing something obvious. I think that it may be a compiler problem.
This is my class I use to convert from RBDL to boost.
class rbdlToBoost {
public:
rbdlToBoost(Model* model) : model(model)
{
q = VectorNd::Zero(model->dof_count);
qd = VectorNd::Zero(model->dof_count);
qdd = VectorNd::Zero(model->dof_count);
tau = VectorNd::Zero(model->dof_count);
}
//3c. Boost uses this 'operator()' function to evaluate the state
// derivative of the pendulum.
void operator() (const state_type &x, state_type &dxdt, const double t)
{
//do stuff
}
private:
Model* model;
VectorNd q, qd, qdd, tau;
};
This is my main I am using to test the integration. This is a minimal example I put together.
#include "rbdl/Model.h"
#include "rbdl/Dynamics.h"
#include "rbdl_model_tests/DynamicTesting.h"
int main(int argc, char const *argv[])
{
int nPts = 100;
double t0 = 0;
double t1 = 3;
double t = 0; //time
double ts = 0; //scaled time
double dtsdt = M_PI/(t1-t0); //dertivative scaled time
double tp = 0;
double dt = (t1-t0)/((double)nPts);
//Integration settings
double absTolVal = 1e-10;
double relTolVal = 1e-6;
double a_x = 1.0 , a_dxdt = 1.0;
Model* model = NULL;
model = new Model();
rbdlToBoost rbdlBoostModel(model);
state_type xState(2);
int steps = 0;
xState[0] = -M_PI/4.0;
xState[1] = 0;
controlled_stepper_type controlled_stepper(
default_error_checker< double , range_algebra , default_operations >
( absTolVal , relTolVal , a_x , a_dxdt )
);
integrate_adaptive(
controlled_stepper ,
model , xState , tp , t , (t-tp)/10 );//This seems to be the problem
tp = t;
return 0;
}
I am getting this error:
~/catkin_ws/src/ambf_control_system/rbdl_model_tests/src/tempDyn.cpp:37:47: required from here
/usr/include/boost/numeric/odeint/stepper/controlled_runge_kutta.hpp:481:12: error: expression cannot be used as a function
sys( x , m_dxdt.m_v ,t );

Answer 1

It turns out it was a simple fix
I just had to change.
I was passing in the wrong variable into the function. I had to pass in my custom class variable (rbdlBoostModel) not my RBDL model (model).
integrate_adaptive(
controlled_stepper ,
model , xState , tp , t , (t-tp)/10 );//This seems to be the problem
to
integrate_adaptive(
controlled_stepper ,
rbdlBoostModel , xState , tp , t , (t-tp)/10 );