Function get_started

example/abs_normal/get_started.cpp:65–140

   }
}
bool get_started(void)
{  bool ok = true;
   //
   using CppAD::AD;
   using CppAD::ADFun;
   //
   size_t n = 3; // size of x
   size_t m = 1; // size of y
   size_t s = 2; // size of u and z
   //
   // record the function f(x)
   CPPAD_TESTVECTOR( AD<double> ) ax(n), ay(m);
   for(size_t j = 0; j < n; j++)
      ax[j] = double(j + 1);
   Independent( ax );
   // for this example, we ensure first absolute value is | x_0 + x_1 |
   AD<double> a0 = abs( ax[0] + ax[1] );
   // and second absolute value is | x_1 + x_2 |
   AD<double> a1 = abs( ax[1] + ax[2] );
   ay[0]         = a0 + a1;
   ADFun<double> f(ax, ay);

   // create its abs_normal representation in g, a
   ADFun<double> g, a;
   f.abs_normal_fun(g, a);

   // check dimension of domain and range space for g
   ok &= g.Domain() == n + s;
   ok &= g.Range() == m + s;

   // check dimension of domain and range space for a
   ok &= a.Domain() == n;
   ok &= a.Range() == s;

   // --------------------------------------------------------------------
   // a(x) has all the operations used to compute f(x), but the sum of the
   // absolute values is not needed for a(x), so optimize it out.
   size_t n_op = f.size_op();
   ok         &= a.size_op() == n_op;
   a.optimize();
   ok         &= a.size_op() < n_op;

   // --------------------------------------------------------------------
   // zero order forward mode calculation using g(x, u)
   CPPAD_TESTVECTOR(double) x(n), u(s), xu(n+s), yz(m+s);
   for(size_t j = 0; j < n; j++)
      x[j] = double(j + 2);
   for(size_t j = 0; j < s; j++)
      u[j] = double(j + n + 2);
   xu = join(x, u);
   yz = g.Forward(0, xu);

   // check y_0(x, u)
   double y0 = u[0] + u[1];
   ok       &= y0 == yz[0];

   // check z_0 (x, u)
   double z0 = x[0] + x[1];