#include "rb_lapack.h"

extern VOID sspev_(char* jobz, char* uplo, integer* n, real* ap, real* w, real* z, integer* ldz, real* work, integer* info);


static VALUE
rblapack_sspev(int argc, VALUE *argv, VALUE self){
  VALUE rblapack_jobz;
  char jobz; 
  VALUE rblapack_uplo;
  char uplo; 
  VALUE rblapack_ap;
  real *ap; 
  VALUE rblapack_w;
  real *w; 
  VALUE rblapack_z;
  real *z; 
  VALUE rblapack_info;
  integer info; 
  VALUE rblapack_ap_out__;
  real *ap_out__;
  real *work;

  integer ldap;
  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  w, z, info, ap = NumRu::Lapack.sspev( jobz, uplo, ap, [:usage => usage, :help => help])\n\n\nFORTRAN MANUAL\n      SUBROUTINE SSPEV( JOBZ, UPLO, N, AP, W, Z, LDZ, WORK, INFO )\n\n*  Purpose\n*  =======\n*\n*  SSPEV computes all the eigenvalues and, optionally, eigenvectors of a\n*  real symmetric matrix A in packed storage.\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*  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)*(2*n-j)/2) = A(i,j) for j<=i<=n.\n*\n*          On exit, AP is overwritten by values generated during the\n*          reduction to tridiagonal form.  If UPLO = 'U', the diagonal\n*          and first superdiagonal of the tridiagonal matrix T overwrite\n*          the corresponding elements of A, and if UPLO = 'L', the\n*          diagonal and first subdiagonal of T overwrite the\n*          corresponding elements of A.\n*\n*  W       (output) REAL array, dimension (N)\n*          If INFO = 0, the eigenvalues in ascending order.\n*\n*  Z       (output) REAL array, dimension (LDZ, N)\n*          If JOBZ = 'V', then if INFO = 0, Z contains the orthonormal\n*          eigenvectors of the matrix A, with the i-th column of Z\n*          holding the eigenvector associated with W(i).\n*          If JOBZ = 'N', then Z is not referenced.\n*\n*  LDZ     (input) INTEGER\n*          The leading dimension of the array Z.  LDZ >= 1, and if\n*          JOBZ = 'V', LDZ >= max(1,N).\n*\n*  WORK    (workspace) REAL array, dimension (3*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, the algorithm failed to converge; i\n*                off-diagonal elements of an intermediate tridiagonal\n*                form did not converge to zero.\n*\n\n*  =====================================================================\n*\n\n");
      return Qnil;
    }
    if (rb_hash_aref(rblapack_options, sUsage) == Qtrue) {
      printf("%s\n", "USAGE:\n  w, z, info, ap = NumRu::Lapack.sspev( jobz, uplo, ap, [: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_jobz = argv[0];
  rblapack_uplo = argv[1];
  rblapack_ap = argv[2];
  if (argc == 3) {
  } else if (rblapack_options != Qnil) {
  } else {
  }

  jobz = StringValueCStr(rblapack_jobz)[0];
  if (!NA_IsNArray(rblapack_ap))
    rb_raise(rb_eArgError, "ap (3th argument) must be NArray");
  if (NA_RANK(rblapack_ap) != 1)
    rb_raise(rb_eArgError, "rank of ap (3th argument) must be %d", 1);
  ldap = NA_SHAPE0(rblapack_ap);
  if (NA_TYPE(rblapack_ap) != NA_SFLOAT)
    rblapack_ap = na_change_type(rblapack_ap, NA_SFLOAT);
  ap = NA_PTR_TYPE(rblapack_ap, real*);
  n = ((int)sqrtf(ldap*8+1.0f)-1)/2;
  uplo = StringValueCStr(rblapack_uplo)[0];
  ldz = lsame_(&jobz,"V") ? MAX(1,n) : 1;
  {
    na_shape_t shape[1];
    shape[0] = n;
    rblapack_w = na_make_object(NA_SFLOAT, 1, shape, cNArray);
  }
  w = NA_PTR_TYPE(rblapack_w, real*);
  {
    na_shape_t shape[2];
    shape[0] = ldz;
    shape[1] = n;
    rblapack_z = na_make_object(NA_SFLOAT, 2, shape, cNArray);
  }
  z = NA_PTR_TYPE(rblapack_z, real*);
  {
    na_shape_t shape[1];
    shape[0] = ldap;
    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__;
  work = ALLOC_N(real, (3*n));

  sspev_(&jobz, &uplo, &n, ap, w, z, &ldz, work, &info);

  free(work);
  rblapack_info = INT2NUM(info);
  return rb_ary_new3(4, rblapack_w, rblapack_z, rblapack_info, rblapack_ap);
}

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

  rb_define_module_function(mLapack, "sspev", rblapack_sspev, -1);
}
