#include "rb_lapack.h"

extern VOID ssytrf_(char* uplo, integer* n, real* a, integer* lda, integer* ipiv, real* work, integer* lwork, integer* info);


static VALUE
rblapack_ssytrf(int argc, VALUE *argv, VALUE self){
  VALUE rblapack_uplo;
  char uplo; 
  VALUE rblapack_a;
  real *a; 
  VALUE rblapack_lwork;
  integer lwork; 
  VALUE rblapack_ipiv;
  integer *ipiv; 
  VALUE rblapack_work;
  real *work; 
  VALUE rblapack_info;
  integer info; 
  VALUE rblapack_a_out__;
  real *a_out__;

  integer lda;
  integer n;

  VALUE rblapack_options;
  if (argc > 0 && TYPE(argv[argc-1]) == T_HASH) {
    argc--;
    rblapack_options = argv[argc];
    if (rb_hash_aref(rblapack_options, sHelp) == Qtrue) {
      printf("%s\n", "USAGE:\n  ipiv, work, info, a = NumRu::Lapack.ssytrf( uplo, a, lwork, [:usage => usage, :help => help])\n\n\nFORTRAN MANUAL\n      SUBROUTINE SSYTRF( UPLO, N, A, LDA, IPIV, WORK, LWORK, INFO )\n\n*  Purpose\n*  =======\n*\n*  SSYTRF computes the factorization of a real symmetric matrix A using\n*  the Bunch-Kaufman diagonal pivoting method.  The form of the\n*  factorization is\n*\n*     A = U*D*U**T  or  A = L*D*L**T\n*\n*  where U (or L) is a product of permutation and unit upper (lower)\n*  triangular matrices, and D is symmetric and block diagonal with \n*  1-by-1 and 2-by-2 diagonal blocks.\n*\n*  This is the blocked version of the algorithm, calling Level 3 BLAS.\n*\n\n*  Arguments\n*  =========\n*\n*  UPLO    (input) CHARACTER*1\n*          = 'U':  Upper triangle of A is stored;\n*          = 'L':  Lower triangle of A is stored.\n*\n*  N       (input) INTEGER\n*          The order of the matrix A.  N >= 0.\n*\n*  A       (input/output) REAL array, dimension (LDA,N)\n*          On entry, the symmetric matrix A.  If UPLO = 'U', the leading\n*          N-by-N upper triangular part of A contains the upper\n*          triangular part of the matrix A, and the strictly lower\n*          triangular part of A is not referenced.  If UPLO = 'L', the\n*          leading N-by-N lower triangular part of A contains the lower\n*          triangular part of the matrix A, and the strictly upper\n*          triangular part of A is not referenced.\n*\n*          On exit, the block diagonal matrix D and the multipliers used\n*          to obtain the factor U or L (see below for further details).\n*\n*  LDA     (input) INTEGER\n*          The leading dimension of the array A.  LDA >= max(1,N).\n*\n*  IPIV    (output) INTEGER array, dimension (N)\n*          Details of the interchanges and the block structure of D.\n*          If IPIV(k) > 0, then rows and columns k and IPIV(k) were\n*          interchanged and D(k,k) is a 1-by-1 diagonal block.\n*          If UPLO = 'U' and IPIV(k) = IPIV(k-1) < 0, then rows and\n*          columns k-1 and -IPIV(k) were interchanged and D(k-1:k,k-1:k)\n*          is a 2-by-2 diagonal block.  If UPLO = 'L' and IPIV(k) =\n*          IPIV(k+1) < 0, then rows and columns k+1 and -IPIV(k) were\n*          interchanged and D(k:k+1,k:k+1) is a 2-by-2 diagonal block.\n*\n*  WORK    (workspace/output) REAL array, dimension (MAX(1,LWORK))\n*          On exit, if INFO = 0, WORK(1) returns the optimal LWORK.\n*\n*  LWORK   (input) INTEGER\n*          The length of WORK.  LWORK >=1.  For best performance\n*          LWORK >= N*NB, where NB is the block size returned by ILAENV.\n*\n*          If LWORK = -1, then a workspace query is assumed; the routine\n*          only calculates the optimal size of the WORK array, returns\n*          this value as the first entry of the WORK array, and no error\n*          message related to LWORK is issued by XERBLA.\n*\n*  INFO    (output) INTEGER\n*          = 0:  successful exit\n*          < 0:  if INFO = -i, the i-th argument had an illegal value\n*          > 0:  if INFO = i, D(i,i) is exactly zero.  The factorization\n*                has been completed, but the block diagonal matrix D is\n*                exactly singular, and division by zero will occur if it\n*                is used to solve a system of equations.\n*\n\n*  Further Details\n*  ===============\n*\n*  If UPLO = 'U', then A = U*D*U', where\n*     U = P(n)*U(n)* ... *P(k)U(k)* ...,\n*  i.e., U is a product of terms P(k)*U(k), where k decreases from n to\n*  1 in steps of 1 or 2, and D is a block diagonal matrix with 1-by-1\n*  and 2-by-2 diagonal blocks D(k).  P(k) is a permutation matrix as\n*  defined by IPIV(k), and U(k) is a unit upper triangular matrix, such\n*  that if the diagonal block D(k) is of order s (s = 1 or 2), then\n*\n*             (   I    v    0   )   k-s\n*     U(k) =  (   0    I    0   )   s\n*             (   0    0    I   )   n-k\n*                k-s   s   n-k\n*\n*  If s = 1, D(k) overwrites A(k,k), and v overwrites A(1:k-1,k).\n*  If s = 2, the upper triangle of D(k) overwrites A(k-1,k-1), A(k-1,k),\n*  and A(k,k), and v overwrites A(1:k-2,k-1:k).\n*\n*  If UPLO = 'L', then A = L*D*L', where\n*     L = P(1)*L(1)* ... *P(k)*L(k)* ...,\n*  i.e., L is a product of terms P(k)*L(k), where k increases from 1 to\n*  n in steps of 1 or 2, and D is a block diagonal matrix with 1-by-1\n*  and 2-by-2 diagonal blocks D(k).  P(k) is a permutation matrix as\n*  defined by IPIV(k), and L(k) is a unit lower triangular matrix, such\n*  that if the diagonal block D(k) is of order s (s = 1 or 2), then\n*\n*             (   I    0     0   )  k-1\n*     L(k) =  (   0    I     0   )  s\n*             (   0    v     I   )  n-k-s+1\n*                k-1   s  n-k-s+1\n*\n*  If s = 1, D(k) overwrites A(k,k), and v overwrites A(k+1:n,k).\n*  If s = 2, the lower triangle of D(k) overwrites A(k,k), A(k+1,k),\n*  and A(k+1,k+1), and v overwrites A(k+2:n,k:k+1).\n*\n*  =====================================================================\n*\n*     .. Local Scalars ..\n      LOGICAL            LQUERY, UPPER\n      INTEGER            IINFO, IWS, J, K, KB, LDWORK, LWKOPT, NB, NBMIN\n*     ..\n*     .. External Functions ..\n      LOGICAL            LSAME\n      INTEGER            ILAENV\n      EXTERNAL           LSAME, ILAENV\n*     ..\n*     .. External Subroutines ..\n      EXTERNAL           SLASYF, SSYTF2, XERBLA\n*     ..\n*     .. Intrinsic Functions ..\n      INTRINSIC          MAX\n*     ..\n\n");
      return Qnil;
    }
    if (rb_hash_aref(rblapack_options, sUsage) == Qtrue) {
      printf("%s\n", "USAGE:\n  ipiv, work, info, a = NumRu::Lapack.ssytrf( uplo, a, lwork, [:usage => usage, :help => help])\n");
      return Qnil;
    } 
  } else
    rblapack_options = Qnil;
  if (argc != 3 && argc != 3)
    rb_raise(rb_eArgError,"wrong number of arguments (%d for 3)", argc);
  rblapack_uplo = argv[0];
  rblapack_a = argv[1];
  rblapack_lwork = argv[2];
  if (argc == 3) {
  } else if (rblapack_options != Qnil) {
  } else {
  }

  uplo = StringValueCStr(rblapack_uplo)[0];
  lwork = NUM2INT(rblapack_lwork);
  if (!NA_IsNArray(rblapack_a))
    rb_raise(rb_eArgError, "a (2th argument) must be NArray");
  if (NA_RANK(rblapack_a) != 2)
    rb_raise(rb_eArgError, "rank of a (2th argument) must be %d", 2);
  lda = NA_SHAPE0(rblapack_a);
  n = NA_SHAPE1(rblapack_a);
  if (NA_TYPE(rblapack_a) != NA_SFLOAT)
    rblapack_a = na_change_type(rblapack_a, NA_SFLOAT);
  a = NA_PTR_TYPE(rblapack_a, real*);
  {
    na_shape_t shape[1];
    shape[0] = n;
    rblapack_ipiv = na_make_object(NA_LINT, 1, shape, cNArray);
  }
  ipiv = NA_PTR_TYPE(rblapack_ipiv, integer*);
  {
    na_shape_t shape[1];
    shape[0] = MAX(1,lwork);
    rblapack_work = na_make_object(NA_SFLOAT, 1, shape, cNArray);
  }
  work = NA_PTR_TYPE(rblapack_work, real*);
  {
    na_shape_t shape[2];
    shape[0] = lda;
    shape[1] = n;
    rblapack_a_out__ = na_make_object(NA_SFLOAT, 2, shape, cNArray);
  }
  a_out__ = NA_PTR_TYPE(rblapack_a_out__, real*);
  MEMCPY(a_out__, a, real, NA_TOTAL(rblapack_a));
  rblapack_a = rblapack_a_out__;
  a = a_out__;

  ssytrf_(&uplo, &n, a, &lda, ipiv, work, &lwork, &info);

  rblapack_info = INT2NUM(info);
  return rb_ary_new3(4, rblapack_ipiv, rblapack_work, rblapack_info, rblapack_a);
}

void
init_lapack_ssytrf(VALUE mLapack, VALUE sH, VALUE sU, VALUE zero){
  sHelp = sH;
  sUsage = sU;
  rblapack_ZERO = zero;

  rb_define_module_function(mLapack, "ssytrf", rblapack_ssytrf, -1);
}
