Printing During Forward Mode: Example and Test
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Printing During Forward Mode: Example and Test
Running
To build this program and run its correctness test see cmake_check .
Source Code `

    # include <cppad/cppad.hpp>

    namespace {
         using std::cout;
         using std::endl;
         using CppAD::AD;

         // use of PrintFor to check for invalid function arguments
         AD<double> check_log(const AD<double>& y)
         {    // check during recording
              if( y <= 0. )
                   cout << "check_log: y = " << y << " is <= 0" << endl;

              // check during zero order forward calculation
              PrintFor(y, "check_log: y == ", y , " which is <= 0\n");

              return log(y);
         }
    }

    void print_for(void)
    {    using CppAD::PrintFor;

         // independent variable vector
         size_t n = 1;
         CPPAD_TESTVECTOR(AD<double>) ax(n);
         ax[0] = 1.;
         Independent(ax);

         // print a VecAD<double>::reference object that is a parameter
         CppAD::VecAD<double> av(1);
         AD<double> Zero(0);
         av[Zero] = 0.;
         PrintFor("v[0] = ", av[Zero]);

         // Print a newline to separate this from previous output,
         // then print an AD<double> object that is a variable.
         PrintFor("\nv[0] + x[0] = ", av[0] + ax[0]);

         // A conditional print that will not generate output when x[0] = 2.
         PrintFor(ax[0], "\n  2. + x[0] = ",   2. + ax[0], "\n");

         // A conditional print that will generate output when x[0] = 2.
         PrintFor(ax[0] - 2., "\n  3. + x[0] = ",   3. + ax[0], "\n");

         // A log evaluations that will result in an error message when x[0] = 2.
         AD<double> var     = 2. - ax[0];
         AD<double> log_var = check_log(var);

         // dependent variable vector
         size_t m = 2;
         CPPAD_TESTVECTOR(AD<double>) ay(m);
         ay[0] = av[Zero] + ax[0];

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

         // zero order forward with x[0] = 2
         CPPAD_TESTVECTOR(double) x(n);
         x[0] = 2.;

         cout << "v[0] = 0" << endl;
         cout << "v[0] + x[0] = 2" << endl;
         cout << "  3. + x[0] = 5" << endl;
         cout << "check_log: y == 0 which is <= 0" << endl;
         // ./makefile.am expects "Test passes" at beginning of next output line
         cout << "Test passes if four lines above repeat below:" << endl;
         f.Forward(0, x);

         return;
    }
    int main(void)
    {    bool ok = true;
         print_for();

         size_t thread;
         for(thread = 0; thread < 2; thread++)
         {    ok &= CppAD::omp_alloc::inuse(thread) == 0;
              ok &= CppAD::omp_alloc::available(thread) == 0;
         }
         if( ! ok )
              return 1;
         return 0;
    }

`
Output
Executing the program above generates the following output: `

         v[0] = 0
         v[0] + x[0] = 2
         Test passes if two lines above repeat below:
         v[0] = 0
         v[0] + x[0] = 2

`

Input File: print_for/print_for.cpp