# include <cppad/local/cppad_assert.hpp>
# include <cppad/check_numeric_type.hpp>
# include <cppad/vector.hpp>

// following needed by gcc under fedora 17 so that exp(double) is defined
# include <cppad/base_require.hpp> 

namespace CppAD {
	template <class Float>
	void sparse_evaluate(
		const CppAD::vector<Float>  &x  ,
		const CppAD::vector<size_t> &i  , 
		const CppAD::vector<size_t> &j  , 
		size_t                       m  ,
		CppAD::vector<Float>       &fm  )
	{
		// check numeric type specifications
		CheckNumericType<Float>();

		size_t k;
		size_t n    = x.size();
		size_t size = 1;
		for(k = 0; k < m; k++)
			size *= n;
		CPPAD_ASSERT_KNOWN(
			fm.size() == size,
			"sparse_evaluate: size of fm not equal n^m"
		);
		for(k = 0; k < size; k++)
			fm[k] = Float(0);

		size_t ell = i.size();
		Float t;
		Float dt_i;
		Float dt_j;
		for(k = 0; k < ell; k++)
		{	t    = exp( x[i[k]] * x[j[k]] );	
			dt_i = t * x[j[k]];
			dt_j = t * x[i[k]];
			switch(m)
			{	case 0:
				fm[0] += t;
				break;

				case 1:
				fm[i[k]] += dt_i;
				fm[j[k]] += dt_j;
				break;

				case 2:
				fm[i[k] * n + i[k]] += dt_i * x[j[k]];
				fm[i[k] * n + j[k]] += t + dt_j * x[j[k]];
				fm[j[k] * n + i[k]] += t + dt_i * x[i[k]];
				fm[j[k] * n + j[k]] += dt_j * x[i[k]];
				break;
			}
		}
			
	}
}