$\newcommand{\W}[1]{ \; #1 \; } \newcommand{\R}[1]{ {\rm #1} } \newcommand{\B}[1]{ {\bf #1} } \newcommand{\D}[2]{ \frac{\partial #1}{\partial #2} } \newcommand{\DD}[3]{ \frac{\partial^2 #1}{\partial #2 \partial #3} } \newcommand{\Dpow}[2]{ \frac{\partial^{#1}}{\partial {#2}^{#1}} } \newcommand{\dpow}[2]{ \frac{ {\rm d}^{#1}}{{\rm d}\, {#2}^{#1}} }$
Print During Zero Order Forward Mode: Example and Test
# include <cppad/cppad.hpp> namespace { using std::endl; using CppAD::AD; // use of PrintFor to check for invalid function arguments AD<double> check_log(const AD<double>& y, std::ostream& s_out) { // check AD<double> value during recording if( y <= 0 ) s_out << "check_log: y == " << y << " which is <= 0\n"; // check double value during zero order forward calculation PrintFor(y, "check_log: y == ", y , " which is <= 0\n"); return log(y); } } bool print_for(void) { bool ok = true; using CppAD::PrintFor; std::stringstream stream_out; // independent variable vector size_t n = 1; CPPAD_TESTVECTOR(AD<double>) ax(n); ax[0] = 1.; // value of the independent variable during recording Independent(ax); // A log evaluations that is OK when x[0] = 1 but not when x[0] = 2. AD<double> var = 2. - ax[0]; AD<double> log_var = check_log(var, stream_out); ok &= stream_out.str() == ""; // dependent variable vector size_t m = 1; CPPAD_TESTVECTOR(AD<double>) ay(m); ay[0] = log_var; // 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.; f.Forward(0, x, stream_out); std::string string_out = stream_out.str(); ok &= stream_out.str() == "check_log: y == 0 which is <= 0\n"; return ok; } 
Input File: example/general/print_for.cpp