Prev Next Value.cpp Headings

Convert From AD to its Base Type: Example and Test
 

# include <cppad/cppad.hpp>

bool Value(void)
{	bool ok = true;
	using CppAD::AD;
	using CppAD::Value;

	// domain space vector
	size_t n = 2;
	CPPAD_TEST_VECTOR< AD<double> > x(n);
	x[0] = 3.;
	x[1] = 4.;

	// check value before recording
	ok &= (Value(x[0]) == 3.);
	ok &= (Value(x[1]) == 4.);

	// declare independent variables and start tape recording
	CppAD::Independent(x);

	// range space vector 
	size_t m = 1;
	CPPAD_TEST_VECTOR< AD<double> > y(m);
	y[0] = - x[1];

	// cannot call Value(x[j]) or Value(y[0]) here (currently variables)
	AD<double> p = 5.;        // p is a parameter (does not depend on x)
	ok &= (Value(p) == 5.);

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

	// can call Value(x[j]) or Value(y[0]) here (currently parameters)
	ok &= (Value(x[0]) ==  3.);
	ok &= (Value(x[1]) ==  4.);
	ok &= (Value(y[0]) == -4.);

	return ok;
}

Input File: example/value.cpp