/* $Id: print_for.cpp 2506 2012-10-24 19:36:49Z bradbell $ */
/* --------------------------------------------------------------------------
CppAD: C++ Algorithmic Differentiation: Copyright (C) 2003-12 Bradley M. Bell

CppAD is distributed under multiple licenses. This distribution is under
the terms of the 
                    GNU General Public License Version 3.

A copy of this license is included in the COPYING file of this distribution.
Please visit http://www.coin-or.org/CppAD/ for information on other licenses.
-------------------------------------------------------------------------- */

/*
$begin print_for_string.cpp$$
$spell
	Cpp
$$

$section Print During Zero Order Forward Mode: Example and Test$$
$index print, zero order forward$$
$index zero, order forward print$$
$index forward, zero order print$$

$code
$verbatim%example/print_for.cpp%0%// BEGIN C++%// END C++%1%$$
$$

$end
*/
// BEGIN C++
# 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;
}
// END C++