#include "rb_lapack.h"

extern VOID sspsv_(char* uplo, integer* n, integer* nrhs, real* ap, integer* ipiv, real* b, integer* ldb, integer* info);


static VALUE
rblapack_sspsv(int argc, VALUE *argv, VALUE self){
  VALUE rblapack_uplo;
  char uplo; 
  VALUE rblapack_ap;
  real *ap; 
  VALUE rblapack_b;
  real *b; 
  VALUE rblapack_ipiv;
  integer *ipiv; 
  VALUE rblapack_info;
  integer info; 
  VALUE rblapack_ap_out__;
  real *ap_out__;
  VALUE rblapack_b_out__;
  real *b_out__;

  integer ldb;
  integer nrhs;
  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, info, ap, b = NumRu::Lapack.sspsv( uplo, ap, b, [:usage => usage, :help => help])\n\n\nFORTRAN MANUAL\n      SUBROUTINE SSPSV( UPLO, N, NRHS, AP, IPIV, B, LDB, INFO )\n\n*  Purpose\n*  =======\n*\n*  SSPSV computes the solution to a real system of linear equations\n*     A * X = B,\n*  where A is an N-by-N symmetric matrix stored in packed format and X\n*  and B are N-by-NRHS matrices.\n*\n*  The diagonal pivoting method is used to factor A as\n*     A = U * D * U**T,  if UPLO = 'U', or\n*     A = L * D * L**T,  if UPLO = 'L',\n*  where U (or L) is a product of permutation and unit upper (lower)\n*  triangular matrices, D is symmetric and block diagonal with 1-by-1\n*  and 2-by-2 diagonal blocks.  The factored form of A is then used to\n*  solve the system of equations A * X = B.\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 number of linear equations, i.e., the order of the\n*          matrix A.  N >= 0.\n*\n*  NRHS    (input) INTEGER\n*          The number of right hand sides, i.e., the number of columns\n*          of the matrix B.  NRHS >= 0.\n*\n*  AP      (input/output) REAL array, dimension (N*(N+1)/2)\n*          On entry, the upper or lower triangle of the symmetric matrix\n*          A, packed columnwise in a linear array.  The j-th column of A\n*          is stored in the array AP as follows:\n*          if UPLO = 'U', AP(i + (j-1)*j/2) = A(i,j) for 1<=i<=j;\n*          if UPLO = 'L', AP(i + (j-1)*(2n-j)/2) = A(i,j) for j<=i<=n.\n*          See below for further details.\n*\n*          On exit, the block diagonal matrix D and the multipliers used\n*          to obtain the factor U or L from the factorization\n*          A = U*D*U**T or A = L*D*L**T as computed by SSPTRF, stored as\n*          a packed triangular matrix in the same storage format as A.\n*\n*  IPIV    (output) INTEGER array, dimension (N)\n*          Details of the interchanges and the block structure of D, as\n*          determined by SSPTRF.  If IPIV(k) > 0, then rows and columns\n*          k and IPIV(k) were interchanged, and D(k,k) is a 1-by-1\n*          diagonal block.  If UPLO = 'U' and IPIV(k) = IPIV(k-1) < 0,\n*          then rows and columns k-1 and -IPIV(k) were interchanged and\n*          D(k-1:k,k-1:k) is a 2-by-2 diagonal block.  If UPLO = 'L' and\n*          IPIV(k) = IPIV(k+1) < 0, then rows and columns k+1 and\n*          -IPIV(k) were interchanged and D(k:k+1,k:k+1) is a 2-by-2\n*          diagonal block.\n*\n*  B       (input/output) REAL array, dimension (LDB,NRHS)\n*          On entry, the N-by-NRHS right hand side matrix B.\n*          On exit, if INFO = 0, the N-by-NRHS solution matrix X.\n*\n*  LDB     (input) INTEGER\n*          The leading dimension of the array B.  LDB >= max(1,N).\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, so the solution could not be\n*                computed.\n*\n\n*  Further Details\n*  ===============\n*\n*  The packed storage scheme is illustrated by the following example\n*  when N = 4, UPLO = 'U':\n*\n*  Two-dimensional storage of the symmetric matrix A:\n*\n*     a11 a12 a13 a14\n*         a22 a23 a24\n*             a33 a34     (aij = aji)\n*                 a44\n*\n*  Packed storage of the upper triangle of A:\n*\n*  AP = [ a11, a12, a22, a13, a23, a33, a14, a24, a34, a44 ]\n*\n*  =====================================================================\n*\n*     .. External Functions ..\n      LOGICAL            LSAME\n      EXTERNAL           LSAME\n*     ..\n*     .. External Subroutines ..\n      EXTERNAL           SSPTRF, SSPTRS, 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, info, ap, b = NumRu::Lapack.sspsv( uplo, ap, b, [: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_ap = argv[1];
  rblapack_b = argv[2];
  if (argc == 3) {
  } else if (rblapack_options != Qnil) {
  } else {
  }

  uplo = StringValueCStr(rblapack_uplo)[0];
  if (!NA_IsNArray(rblapack_b))
    rb_raise(rb_eArgError, "b (3th argument) must be NArray");
  if (NA_RANK(rblapack_b) != 2)
    rb_raise(rb_eArgError, "rank of b (3th argument) must be %d", 2);
  ldb = NA_SHAPE0(rblapack_b);
  nrhs = NA_SHAPE1(rblapack_b);
  if (NA_TYPE(rblapack_b) != NA_SFLOAT)
    rblapack_b = na_change_type(rblapack_b, NA_SFLOAT);
  b = NA_PTR_TYPE(rblapack_b, real*);
  n = ldb;
  if (!NA_IsNArray(rblapack_ap))
    rb_raise(rb_eArgError, "ap (2th argument) must be NArray");
  if (NA_RANK(rblapack_ap) != 1)
    rb_raise(rb_eArgError, "rank of ap (2th argument) must be %d", 1);
  if (NA_SHAPE0(rblapack_ap) != (n*(n+1)/2))
    rb_raise(rb_eRuntimeError, "shape 0 of ap must be %d", n*(n+1)/2);
  if (NA_TYPE(rblapack_ap) != NA_SFLOAT)
    rblapack_ap = na_change_type(rblapack_ap, NA_SFLOAT);
  ap = NA_PTR_TYPE(rblapack_ap, 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] = n*(n+1)/2;
    rblapack_ap_out__ = na_make_object(NA_SFLOAT, 1, shape, cNArray);
  }
  ap_out__ = NA_PTR_TYPE(rblapack_ap_out__, real*);
  MEMCPY(ap_out__, ap, real, NA_TOTAL(rblapack_ap));
  rblapack_ap = rblapack_ap_out__;
  ap = ap_out__;
  {
    na_shape_t shape[2];
    shape[0] = ldb;
    shape[1] = nrhs;
    rblapack_b_out__ = na_make_object(NA_SFLOAT, 2, shape, cNArray);
  }
  b_out__ = NA_PTR_TYPE(rblapack_b_out__, real*);
  MEMCPY(b_out__, b, real, NA_TOTAL(rblapack_b));
  rblapack_b = rblapack_b_out__;
  b = b_out__;

  sspsv_(&uplo, &n, &nrhs, ap, ipiv, b, &ldb, &info);

  rblapack_info = INT2NUM(info);
  return rb_ary_new3(4, rblapack_ipiv, rblapack_info, rblapack_ap, rblapack_b);
}

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

  rb_define_module_function(mLapack, "sspsv", rblapack_sspsv, -1);
}
