# include <cmath>
# include <f2cad/d9knus.hpp>

test_result d9knus(void)
{	bool ok = true;

	// independent variable
	integer    n = 1;          // number of independent variables
	doublereal x[1];           // vector of independent variables
	x[0]         = .75;        // value of independent variable
	f2cad::Independent(n, x);  // declare x as independent variable vector

	// call the routine
	doublereal xnu = .5;
	doublereal bknu, bknu1;
	integer    iswtch;  
	f2cad::d9knus_(&xnu, x+0, &bknu, &bknu1, &iswtch);

	// dependent variables 
	integer     m = 1;          // number of dependent variables
	doublereal  f[1];           // vector of dependent variables
	f[0] = bknu;                // value f[0] = K_nu (x[0]) * exp( x[0] )
	f2cad::Dependent(m, f);     // declare f as dependent variable vector

	// check function value
	double x0    = f2cad::Value( x[0] );
	double f0    = f2cad::Value( f[0] );
	double pi    = 4. * std::atan(1.);
	double check = 1. / sqrt( 2. * x0 / pi );
	ok          &= f2cad::near_equal(f0, check, 1e-10, 1e-10);

	// Evaluate the derivative of f[0] w.r.t x[0]
	double p = f2cad::Partial<doublereal>(0, 0);
	check    = - check * check * check / pi;
	ok      &= f2cad::near_equal(p, check, 1e-10, 1e-10);

	if( ok ) 
		return test_pass;
	return test_fail;
}