AD Binary Comparison Operators: Example and Test
Keywords: ad binary comparison operators: example test compare < <= > >= == !=

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AD Binary Comparison Operators: Example and Test
`

    # include <cppad/cppad.hpp>

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

    	// declare independent variables and start tape recording
    	size_t n  = 2;
    	double x0 = 0.5;
    	double x1 = 1.5;
    	CPPAD_TESTVECTOR(AD<double>) x(n);
    	x[0]      = x0;
    	x[1]      = x1;
    	CppAD::Independent(x);

    	// some binary comparision operations
    	AD<double> p;
    	if( x[0] < x[1] )
    		p = x[0];   // values in x choose this case
    	else	p = x[1];
    	if( x[0] <= x[1] )
    		p *= x[0];  // values in x choose this case
    	else	p *= x[1];
    	if( x[0] >  x[1] )
    		p *= x[0];
    	else	p *= x[1];  // values in x choose this case
    	if( x[0] >= x[1] )
    		p *= x[0];
    	else	p *= x[1];  // values in x choose this case
    	if( x[0] == x[1] )
    		p *= x[0];
    	else	p *= x[1];  // values in x choose this case
    	if( x[0] != x[1] )
    		p *= x[0];  // values in x choose this case
    	else	p *= x[1];

    	// dependent variable vector
    	size_t m = 1;
    	CPPAD_TESTVECTOR(AD<double>) y(m);
    	y[0] = p;

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

    	// check value
    	ok &= NearEqual(y[0] , x0*x0*x1*x1*x1*x0,  1e-10 , 1e-10);

    	// forward computation of partials w.r.t. x[0]
    	CPPAD_TESTVECTOR(double) dx(n);
    	CPPAD_TESTVECTOR(double) dy(m);
    	dx[0] = 1.;
    	dx[1] = 0.;
    	dy    = f.Forward(1, dx);
    	ok   &= NearEqual(dy[0], 3.*x0*x0*x1*x1*x1, 1e-10, 1e-10);

    	// forward computation of partials w.r.t. x[1]
    	dx[0] = 0.;
    	dx[1] = 1.;
    	dy    = f.Forward(1, dx);
    	ok   &= NearEqual(dy[0], 3.*x0*x0*x1*x1*x0, 1e-10, 1e-10);

    	// reverse computation of derivative of y[0]
    	CPPAD_TESTVECTOR(double)  w(m);
    	CPPAD_TESTVECTOR(double) dw(n);
    	w[0]  = 1.;
    	dw    = f.Reverse(1, w);
    	ok   &= NearEqual(dw[0], 3.*x0*x0*x1*x1*x1, 1e-10, 1e-10);
    	ok   &= NearEqual(dw[1], 3.*x0*x0*x1*x1*x0, 1e-10, 1e-10);

    	return ok;
    }

`

Input File: example/compare.cpp