# include <cppad/cppad.hpp>
# include <cmath>

bool pow_int(void)
{     bool ok = true;
     using CppAD::AD;
     using CppAD::NearEqual;
     double eps99 = 99.0 * std::numeric_limits<double>::epsilon();

     // declare independent variables and start tape recording
     size_t n  = 1;
     double x0 = -0.5;
     CPPAD_TESTVECTOR(AD<double>) x(n);
     x[0]      = x0;
     CppAD::Independent(x);

     // dependent variable vector
     size_t m = 7;
     CPPAD_TESTVECTOR(AD<double>) y(m);
     int i;
     for(i = 0; i < int(m); i++)
          y[i] = CppAD::pow(x[0], i - 3);

     // create f: x -> y and stop tape recording
     CppAD::ADFun<double> f(x, y);

     // check value
     double check;
     for(i = 0; i < int(m); i++)
     {     check = std::pow(x0, double(i - 3));
          ok &= NearEqual(y[i] , check,  eps99 , eps99);
     }

     // forward computation of first partial w.r.t. x[0]
     CPPAD_TESTVECTOR(double) dx(n);
     CPPAD_TESTVECTOR(double) dy(m);
     dx[0] = 1.;
     dy    = f.Forward(1, dx);
     for(i = 0; i < int(m); i++)
     {     check = double(i-3) * std::pow(x0, double(i - 4));
          ok &= NearEqual(dy[i] , check,  eps99 , eps99);
     }

     // reverse computation of derivative of y[i]
     CPPAD_TESTVECTOR(double)  w(m);
     CPPAD_TESTVECTOR(double) dw(n);
     for(i = 0; i < int(m); i++)
          w[i] = 0.;
     for(i = 0; i < int(m); i++)
     {     w[i] = 1.;
          dw    = f.Reverse(1, w);
          check = double(i-3) * std::pow(x0, double(i - 4));
          ok &= NearEqual(dw[0] , check,  eps99 , eps99);
          w[i] = 0.;
     }

     return ok;
}