#include "rb_lapack.h"

extern VOID ssteqr_(char* compz, integer* n, real* d, real* e, real* z, integer* ldz, real* work, integer* info);


static VALUE
rblapack_ssteqr(int argc, VALUE *argv, VALUE self){
  VALUE rblapack_compz;
  char compz; 
  VALUE rblapack_d;
  real *d; 
  VALUE rblapack_e;
  real *e; 
  VALUE rblapack_z;
  real *z; 
  VALUE rblapack_info;
  integer info; 
  VALUE rblapack_d_out__;
  real *d_out__;
  VALUE rblapack_e_out__;
  real *e_out__;
  VALUE rblapack_z_out__;
  real *z_out__;
  real *work;

  integer n;
  integer ldz;

  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  info, d, e, z = NumRu::Lapack.ssteqr( compz, d, e, z, [:usage => usage, :help => help])\n\n\nFORTRAN MANUAL\n      SUBROUTINE SSTEQR( COMPZ, N, D, E, Z, LDZ, WORK, INFO )\n\n*  Purpose\n*  =======\n*\n*  SSTEQR computes all eigenvalues and, optionally, eigenvectors of a\n*  symmetric tridiagonal matrix using the implicit QL or QR method.\n*  The eigenvectors of a full or band symmetric matrix can also be found\n*  if SSYTRD or SSPTRD or SSBTRD has been used to reduce this matrix to\n*  tridiagonal form.\n*\n\n*  Arguments\n*  =========\n*\n*  COMPZ   (input) CHARACTER*1\n*          = 'N':  Compute eigenvalues only.\n*          = 'V':  Compute eigenvalues and eigenvectors of the original\n*                  symmetric matrix.  On entry, Z must contain the\n*                  orthogonal matrix used to reduce the original matrix\n*                  to tridiagonal form.\n*          = 'I':  Compute eigenvalues and eigenvectors of the\n*                  tridiagonal matrix.  Z is initialized to the identity\n*                  matrix.\n*\n*  N       (input) INTEGER\n*          The order of the matrix.  N >= 0.\n*\n*  D       (input/output) REAL array, dimension (N)\n*          On entry, the diagonal elements of the tridiagonal matrix.\n*          On exit, if INFO = 0, the eigenvalues in ascending order.\n*\n*  E       (input/output) REAL array, dimension (N-1)\n*          On entry, the (n-1) subdiagonal elements of the tridiagonal\n*          matrix.\n*          On exit, E has been destroyed.\n*\n*  Z       (input/output) REAL array, dimension (LDZ, N)\n*          On entry, if  COMPZ = 'V', then Z contains the orthogonal\n*          matrix used in the reduction to tridiagonal form.\n*          On exit, if INFO = 0, then if  COMPZ = 'V', Z contains the\n*          orthonormal eigenvectors of the original symmetric matrix,\n*          and if COMPZ = 'I', Z contains the orthonormal eigenvectors\n*          of the symmetric tridiagonal matrix.\n*          If COMPZ = 'N', then Z is not referenced.\n*\n*  LDZ     (input) INTEGER\n*          The leading dimension of the array Z.  LDZ >= 1, and if\n*          eigenvectors are desired, then  LDZ >= max(1,N).\n*\n*  WORK    (workspace) REAL array, dimension (max(1,2*N-2))\n*          If COMPZ = 'N', then WORK is not referenced.\n*\n*  INFO    (output) INTEGER\n*          = 0:  successful exit\n*          < 0:  if INFO = -i, the i-th argument had an illegal value\n*          > 0:  the algorithm has failed to find all the eigenvalues in\n*                a total of 30*N iterations; if INFO = i, then i\n*                elements of E have not converged to zero; on exit, D\n*                and E contain the elements of a symmetric tridiagonal\n*                matrix which is orthogonally similar to the original\n*                matrix.\n*\n\n*  =====================================================================\n*\n\n");
      return Qnil;
    }
    if (rb_hash_aref(rblapack_options, sUsage) == Qtrue) {
      printf("%s\n", "USAGE:\n  info, d, e, z = NumRu::Lapack.ssteqr( compz, d, e, z, [:usage => usage, :help => help])\n");
      return Qnil;
    } 
  } else
    rblapack_options = Qnil;
  if (argc != 4 && argc != 4)
    rb_raise(rb_eArgError,"wrong number of arguments (%d for 4)", argc);
  rblapack_compz = argv[0];
  rblapack_d = argv[1];
  rblapack_e = argv[2];
  rblapack_z = argv[3];
  if (argc == 4) {
  } else if (rblapack_options != Qnil) {
  } else {
  }

  compz = StringValueCStr(rblapack_compz)[0];
  if (!NA_IsNArray(rblapack_z))
    rb_raise(rb_eArgError, "z (4th argument) must be NArray");
  if (NA_RANK(rblapack_z) != 2)
    rb_raise(rb_eArgError, "rank of z (4th argument) must be %d", 2);
  ldz = NA_SHAPE0(rblapack_z);
  n = NA_SHAPE1(rblapack_z);
  if (NA_TYPE(rblapack_z) != NA_SFLOAT)
    rblapack_z = na_change_type(rblapack_z, NA_SFLOAT);
  z = NA_PTR_TYPE(rblapack_z, real*);
  if (!NA_IsNArray(rblapack_d))
    rb_raise(rb_eArgError, "d (2th argument) must be NArray");
  if (NA_RANK(rblapack_d) != 1)
    rb_raise(rb_eArgError, "rank of d (2th argument) must be %d", 1);
  if (NA_SHAPE0(rblapack_d) != n)
    rb_raise(rb_eRuntimeError, "shape 0 of d must be the same as shape 1 of z");
  if (NA_TYPE(rblapack_d) != NA_SFLOAT)
    rblapack_d = na_change_type(rblapack_d, NA_SFLOAT);
  d = NA_PTR_TYPE(rblapack_d, real*);
  if (!NA_IsNArray(rblapack_e))
    rb_raise(rb_eArgError, "e (3th argument) must be NArray");
  if (NA_RANK(rblapack_e) != 1)
    rb_raise(rb_eArgError, "rank of e (3th argument) must be %d", 1);
  if (NA_SHAPE0(rblapack_e) != (n-1))
    rb_raise(rb_eRuntimeError, "shape 0 of e must be %d", n-1);
  if (NA_TYPE(rblapack_e) != NA_SFLOAT)
    rblapack_e = na_change_type(rblapack_e, NA_SFLOAT);
  e = NA_PTR_TYPE(rblapack_e, real*);
  {
    int shape[1];
    shape[0] = n;
    rblapack_d_out__ = na_make_object(NA_SFLOAT, 1, shape, cNArray);
  }
  d_out__ = NA_PTR_TYPE(rblapack_d_out__, real*);
  MEMCPY(d_out__, d, real, NA_TOTAL(rblapack_d));
  rblapack_d = rblapack_d_out__;
  d = d_out__;
  {
    int shape[1];
    shape[0] = n-1;
    rblapack_e_out__ = na_make_object(NA_SFLOAT, 1, shape, cNArray);
  }
  e_out__ = NA_PTR_TYPE(rblapack_e_out__, real*);
  MEMCPY(e_out__, e, real, NA_TOTAL(rblapack_e));
  rblapack_e = rblapack_e_out__;
  e = e_out__;
  {
    int shape[2];
    shape[0] = ldz;
    shape[1] = n;
    rblapack_z_out__ = na_make_object(NA_SFLOAT, 2, shape, cNArray);
  }
  z_out__ = NA_PTR_TYPE(rblapack_z_out__, real*);
  MEMCPY(z_out__, z, real, NA_TOTAL(rblapack_z));
  rblapack_z = rblapack_z_out__;
  z = z_out__;
  work = ALLOC_N(real, (lsame_(&compz,"N") ? 0 : MAX(1,2*n-2)));

  ssteqr_(&compz, &n, d, e, z, &ldz, work, &info);

  free(work);
  rblapack_info = INT2NUM(info);
  return rb_ary_new3(4, rblapack_info, rblapack_d, rblapack_e, rblapack_z);
}

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

  rb_define_module_function(mLapack, "ssteqr", rblapack_ssteqr, -1);
}
