cppad
  • Table of Contents
  • user_guide
    • Install
    • Theory
    • AD
      • ad_ctor
      • ad_assign
      • Convert
        • Value
        • Integer
        • ad_to_string
        • ad_input
        • ad_output
        • PrintFor
          • print_for_cout.cpp
          • print_for_string.cpp
        • Var2Par
      • ADValued
      • bool_valued
      • VecAD
      • base_require
    • ADFun
    • preprocessor
    • multi_thread
    • utility
    • ipopt_solve
    • Example
    • speed
  • appendix
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cppad
  • user_guide
  • AD
  • Convert
  • PrintFor
  • print_for_cout.cpp
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\(\newcommand{\W}[1]{ \; #1 \; }\) \(\newcommand{\R}[1]{ {\rm #1} }\) \(\newcommand{\B}[1]{ {\bf #1} }\) \(\newcommand{\D}[2]{ \frac{\partial #1}{\partial #2} }\) \(\newcommand{\DD}[3]{ \frac{\partial^2 #1}{\partial #2 \partial #3} }\) \(\newcommand{\Dpow}[2]{ \frac{\partial^{#1}}{\partial {#2}^{#1}} }\) \(\newcommand{\dpow}[2]{ \frac{ {\rm d}^{#1}}{{\rm d}\, {#2}^{#1}} }\)

print_for_cout.cpp

Printing During Forward Mode: Example and Test

  • Running

  • Source Code

  • Output

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)
{  print_for();

   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
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