#include "rb_lapack.h"

extern VOID ssyevd_(char* jobz, char* uplo, integer* n, real* a, integer* lda, real* w, real* work, integer* lwork, integer* iwork, integer* liwork, integer* info);


static VALUE
rblapack_ssyevd(int argc, VALUE *argv, VALUE self){
  VALUE rblapack_jobz;
  char jobz; 
  VALUE rblapack_uplo;
  char uplo; 
  VALUE rblapack_a;
  real *a; 
  VALUE rblapack_lwork;
  integer lwork; 
  VALUE rblapack_liwork;
  integer liwork; 
  VALUE rblapack_w;
  real *w; 
  VALUE rblapack_work;
  real *work; 
  VALUE rblapack_iwork;
  integer *iwork; 
  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  w, work, iwork, info, a = NumRu::Lapack.ssyevd( jobz, uplo, a, [:lwork => lwork, :liwork => liwork, :usage => usage, :help => help])\n\n\nFORTRAN MANUAL\n      SUBROUTINE SSYEVD( JOBZ, UPLO, N, A, LDA, W, WORK, LWORK, IWORK, LIWORK, INFO )\n\n*  Purpose\n*  =======\n*\n*  SSYEVD computes all eigenvalues and, optionally, eigenvectors of a\n*  real symmetric matrix A. If eigenvectors are desired, it uses a\n*  divide and conquer algorithm.\n*\n*  The divide and conquer algorithm makes very mild assumptions about\n*  floating point arithmetic. It will work on machines with a guard\n*  digit in add/subtract, or on those binary machines without guard\n*  digits which subtract like the Cray X-MP, Cray Y-MP, Cray C-90, or\n*  Cray-2. It could conceivably fail on hexadecimal or decimal machines\n*  without guard digits, but we know of none.\n*\n*  Because of large use of BLAS of level 3, SSYEVD needs N**2 more\n*  workspace than SSYEVX.\n*\n\n*  Arguments\n*  =========\n*\n*  JOBZ    (input) CHARACTER*1\n*          = 'N':  Compute eigenvalues only;\n*          = 'V':  Compute eigenvalues and eigenvectors.\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\n*          leading N-by-N upper triangular part of A contains the\n*          upper triangular part of the matrix A.  If UPLO = 'L',\n*          the leading N-by-N lower triangular part of A contains\n*          the lower triangular part of the matrix A.\n*          On exit, if JOBZ = 'V', then if INFO = 0, A contains the\n*          orthonormal eigenvectors of the matrix A.\n*          If JOBZ = 'N', then on exit the lower triangle (if UPLO='L')\n*          or the upper triangle (if UPLO='U') of A, including the\n*          diagonal, is destroyed.\n*\n*  LDA     (input) INTEGER\n*          The leading dimension of the array A.  LDA >= max(1,N).\n*\n*  W       (output) REAL array, dimension (N)\n*          If INFO = 0, the eigenvalues in ascending order.\n*\n*  WORK    (workspace/output) REAL array,\n*                                         dimension (LWORK)\n*          On exit, if INFO = 0, WORK(1) returns the optimal LWORK.\n*\n*  LWORK   (input) INTEGER\n*          The dimension of the array WORK.\n*          If N <= 1,               LWORK must be at least 1.\n*          If JOBZ = 'N' and N > 1, LWORK must be at least 2*N+1.\n*          If JOBZ = 'V' and N > 1, LWORK must be at least \n*                                                1 + 6*N + 2*N**2.\n*\n*          If LWORK = -1, then a workspace query is assumed; the routine\n*          only calculates the optimal sizes of the WORK and IWORK\n*          arrays, returns these values as the first entries of the WORK\n*          and IWORK arrays, and no error message related to LWORK or\n*          LIWORK is issued by XERBLA.\n*\n*  IWORK   (workspace/output) INTEGER array, dimension (MAX(1,LIWORK))\n*          On exit, if INFO = 0, IWORK(1) returns the optimal LIWORK.\n*\n*  LIWORK  (input) INTEGER\n*          The dimension of the array IWORK.\n*          If N <= 1,                LIWORK must be at least 1.\n*          If JOBZ  = 'N' and N > 1, LIWORK must be at least 1.\n*          If JOBZ  = 'V' and N > 1, LIWORK must be at least 3 + 5*N.\n*\n*          If LIWORK = -1, then a workspace query is assumed; the\n*          routine only calculates the optimal sizes of the WORK and\n*          IWORK arrays, returns these values as the first entries of\n*          the WORK and IWORK arrays, and no error message related to\n*          LWORK or LIWORK 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 and JOBZ = 'N', then the algorithm failed\n*                to converge; i off-diagonal elements of an intermediate\n*                tridiagonal form did not converge to zero;\n*                if INFO = i and JOBZ = 'V', then the algorithm failed\n*                to compute an eigenvalue while working on the submatrix\n*                lying in rows and columns INFO/(N+1) through\n*                mod(INFO,N+1).\n*\n\n*  Further Details\n*  ===============\n*\n*  Based on contributions by\n*     Jeff Rutter, Computer Science Division, University of California\n*     at Berkeley, USA\n*  Modified by Francoise Tisseur, University of Tennessee.\n*\n*  Modified description of INFO. Sven, 16 Feb 05.\n*  =====================================================================\n*\n\n");
      return Qnil;
    }
    if (rb_hash_aref(rblapack_options, sUsage) == Qtrue) {
      printf("%s\n", "USAGE:\n  w, work, iwork, info, a = NumRu::Lapack.ssyevd( jobz, uplo, a, [:lwork => lwork, :liwork => liwork, :usage => usage, :help => help])\n");
      return Qnil;
    } 
  } else
    rblapack_options = Qnil;
  if (argc != 3 && argc != 5)
    rb_raise(rb_eArgError,"wrong number of arguments (%d for 3)", argc);
  rblapack_jobz = argv[0];
  rblapack_uplo = argv[1];
  rblapack_a = argv[2];
  if (argc == 5) {
    rblapack_lwork = argv[3];
    rblapack_liwork = argv[4];
  } else if (rblapack_options != Qnil) {
    rblapack_lwork = rb_hash_aref(rblapack_options, ID2SYM(rb_intern("lwork")));
    rblapack_liwork = rb_hash_aref(rblapack_options, ID2SYM(rb_intern("liwork")));
  } else {
    rblapack_lwork = Qnil;
    rblapack_liwork = Qnil;
  }

  jobz = StringValueCStr(rblapack_jobz)[0];
  if (!NA_IsNArray(rblapack_a))
    rb_raise(rb_eArgError, "a (3th argument) must be NArray");
  if (NA_RANK(rblapack_a) != 2)
    rb_raise(rb_eArgError, "rank of a (3th 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*);
  if (rblapack_liwork == Qnil)
    liwork = n<=1 ? 1 : lsame_(&jobz,"N") ? 1 : lsame_(&jobz,"V") ? 3+5*n : 0;
  else {
    liwork = NUM2INT(rblapack_liwork);
  }
  uplo = StringValueCStr(rblapack_uplo)[0];
  if (rblapack_lwork == Qnil)
    lwork = n<=1 ? 1 : lsame_(&jobz,"N") ? 2*n+1 : lsame_(&jobz,"V") ? 1+6*n+2*n*n : 0;
  else {
    lwork = NUM2INT(rblapack_lwork);
  }
  {
    int shape[1];
    shape[0] = n;
    rblapack_w = na_make_object(NA_SFLOAT, 1, shape, cNArray);
  }
  w = NA_PTR_TYPE(rblapack_w, real*);
  {
    int shape[1];
    shape[0] = MAX(1,lwork);
    rblapack_work = na_make_object(NA_SFLOAT, 1, shape, cNArray);
  }
  work = NA_PTR_TYPE(rblapack_work, real*);
  {
    int shape[1];
    shape[0] = MAX(1,liwork);
    rblapack_iwork = na_make_object(NA_LINT, 1, shape, cNArray);
  }
  iwork = NA_PTR_TYPE(rblapack_iwork, integer*);
  {
    int 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__;

  ssyevd_(&jobz, &uplo, &n, a, &lda, w, work, &lwork, iwork, &liwork, &info);

  rblapack_info = INT2NUM(info);
  return rb_ary_new3(5, rblapack_w, rblapack_work, rblapack_iwork, rblapack_info, rblapack_a);
}

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

  rb_define_module_function(mLapack, "ssyevd", rblapack_ssyevd, -1);
}
