/*******************************************************
 * Copyright (c) 2014, ArrayFire
 * All rights reserved.
 *
 * This file is distributed under 3-clause BSD license.
 * The complete license agreement can be obtained at:
 * http://arrayfire.com/licenses/BSD-3-Clause
 ********************************************************/

#if defined(WITH_LINEAR_ALGEBRA)
#include <cpu/cpu_helper.hpp>
#include <cpu/cpu_inverse.hpp>
#include <cpu/cpu_lu.hpp>
#include <copy.hpp>

namespace opencl
{
namespace cpu
{

template<typename T>
using getri_func_def = int (*)(ORDER_TYPE, int,
                               T *, int,
                               const int *);

#define INV_FUNC_DEF( FUNC )                                        \
template<typename T> FUNC##_func_def<T> FUNC##_func();

#define INV_FUNC( FUNC, TYPE, PREFIX )                              \
template<> FUNC##_func_def<TYPE>     FUNC##_func<TYPE>()            \
{ return & LAPACK_NAME(PREFIX##FUNC); }

INV_FUNC_DEF( getri )
INV_FUNC(getri , float  , s)
INV_FUNC(getri , double , d)
INV_FUNC(getri , cfloat , c)
INV_FUNC(getri , cdouble, z)

template<typename T>
Array<T> inverse(const Array<T> &in)
{
    int M = in.dims()[0];
    //int N = in.dims()[1];

    // This condition is already handled in opencl/inverse.cpp
    //if (M != N) {
        //Array<T> I = identity<T>(in.dims());
        //return solve(in, I);
    //}

    Array<T> A = copyArray<T>(in);

    Array<int> pivot = cpu::lu_inplace<T>(A, false);


    std::shared_ptr<T>   aPtr = A.getMappedPtr();
    std::shared_ptr<int> pPtr = pivot.getMappedPtr();

    getri_func<T>()(AF_LAPACK_COL_MAJOR, M,
                    aPtr.get(), A.strides()[1],
                    pPtr.get());

    return A;
}

#define INSTANTIATE(T)                                                                   \
    template Array<T> inverse<T> (const Array<T> &in);

INSTANTIATE(float)
INSTANTIATE(cfloat)
INSTANTIATE(double)
INSTANTIATE(cdouble)

}
}
#endif  // WITH_LINEAR_ALGEBRA
