/* --------------------------------------------------------------------------
CppAD: C++ Algorithmic Differentiation: Copyright (C) 2003-17 Bradley M. Bell

CppAD is distributed under the terms of the
             Eclipse Public License Version 2.0.

This Source Code may also be made available under the following
Secondary License when the conditions for such availability set forth
in the Eclipse Public License, Version 2.0 are satisfied:
      GNU General Public License, Version 2.0 or later.
---------------------------------------------------------------------------- */

/*
$begin check_numeric_type.cpp$$

$section The CheckNumericType Function: Example and Test$$

$srcfile%example/utility/check_numeric_type.cpp%0%// BEGIN C++%// END C++%1%$$

$end
*/
// BEGIN C++

# include <cppad/utility/check_numeric_type.hpp>
# include <cppad/utility/near_equal.hpp>


// Chosing a value between 1 and 10 selects a numeric class properity to be
// omitted and result in an error message being generated
# define CppADMyTypeOmit 0

namespace { // Empty namespace

    // -------------------------------------------------------------------
    class MyType {
    private:
        double d;
    public:
        // constructor from void
        MyType(void) : d(0.)
        { }
        // constructor from an int
        MyType(int d_) : d(d_)
        { }
        // copy constuctor
        MyType(const MyType &x)
        {   d = x.d; }
        // assignment operator
        void operator = (const MyType &x)
        {   d = x.d; }
        // member function that converts to double
        double Double(void) const
        {   return d; }
# if CppADMyTypeOmit != 1
        // unary plus
        MyType operator + (void) const
        {   MyType x;
            x.d =  d;
            return x;
        }
# endif
# if CppADMyTypeOmit != 2
        // unary plus
        MyType operator - (void) const
        {   MyType x;
            x.d = - d;
            return x;
        }
# endif
# if CppADMyTypeOmit != 3
        // binary addition
        MyType operator + (const MyType &x) const
        {   MyType y;
            y.d = d + x.d ;
            return y;
        }
# endif
# if CppADMyTypeOmit != 4
        // binary subtraction
        MyType operator - (const MyType &x) const
        {   MyType y;
            y.d = d - x.d ;
            return y;
        }
# endif
# if CppADMyTypeOmit != 5
        // binary multiplication
        MyType operator * (const MyType &x) const
        {   MyType y;
            y.d = d * x.d ;
            return y;
        }
# endif
# if CppADMyTypeOmit != 6
        // binary division
        MyType operator / (const MyType &x) const
        {   MyType y;
            y.d = d / x.d ;
            return y;
        }
# endif
# if CppADMyTypeOmit != 7
        // compound assignment addition
        void operator += (const MyType &x)
        {   d += x.d; }
# endif
# if CppADMyTypeOmit != 8
        // compound assignment subtraction
        void operator -= (const MyType &x)
        {   d -= x.d; }
# endif
# if CppADMyTypeOmit != 9
        // compound assignment multiplication
        void operator *= (const MyType &x)
        {   d *= x.d; }
# endif
# if CppADMyTypeOmit != 10
        // compound assignment division
        void operator /= (const MyType &x)
        {   d /= x.d; }
# endif
    };
    // -------------------------------------------------------------------
    /*
    Solve: A[0] * x[0] + A[1] * x[1] = b[0]
           A[2] * x[0] + A[3] * x[1] = b[1]
    */
    template <class NumericType>
    void Solve(NumericType *A, NumericType *x, NumericType *b)
    {
        // make sure NumericType satisfies its conditions
        CppAD::CheckNumericType<NumericType>();

        // copy b to x
        x[0] = b[0];
        x[1] = b[1];

        // copy A to work space
        NumericType W[4];
        W[0] = A[0];
        W[1] = A[1];
        W[2] = A[2];
        W[3] = A[3];

        // divide first row by W(1,1)
        W[1] /= W[0];
        x[0] /= W[0];
        W[0] = NumericType(1);

        // subtract W(2,1) times first row from second row
        W[3] -= W[2] * W[1];
        x[1] -= W[2] * x[0];
        W[2] = NumericType(0);

        // divide second row by W(2, 2)
        x[1] /= W[3];
        W[3]  = NumericType(1);

        // use first row to solve for x[0]
        x[0] -= W[1] * x[1];
    }
} // End Empty namespace

bool CheckNumericType(void)
{   bool ok  = true;
    using CppAD::NearEqual;
    double eps99 = 99.0 * std::numeric_limits<double>::epsilon();

    MyType A[4];
    A[0] = MyType(1); A[1] = MyType(2);
    A[2] = MyType(3); A[3] = MyType(4);

    MyType b[2];
    b[0] = MyType(1);
    b[1] = MyType(2);

    MyType x[2];
    Solve(A, x, b);

    MyType sum;
    sum = A[0] * x[0] + A[1] * x[1];
    ok &= NearEqual(sum.Double(), b[0].Double(), eps99, eps99);

    sum = A[2] * x[0] + A[3] * x[1];
    ok &= NearEqual(sum.Double(), b[1].Double(), eps99, eps99);

    return ok;
}

// END C++
