#include "rb_lapack.h"

extern VOID ssygs2_(integer* itype, char* uplo, integer* n, real* a, integer* lda, real* b, integer* ldb, integer* info);


static VALUE
rblapack_ssygs2(int argc, VALUE *argv, VALUE self){
  VALUE rblapack_itype;
  integer itype; 
  VALUE rblapack_uplo;
  char uplo; 
  VALUE rblapack_a;
  real *a; 
  VALUE rblapack_b;
  real *b; 
  VALUE rblapack_info;
  integer info; 
  VALUE rblapack_a_out__;
  real *a_out__;

  integer lda;
  integer n;
  integer ldb;

  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, a = NumRu::Lapack.ssygs2( itype, uplo, a, b, [:usage => usage, :help => help])\n\n\nFORTRAN MANUAL\n      SUBROUTINE SSYGS2( ITYPE, UPLO, N, A, LDA, B, LDB, INFO )\n\n*  Purpose\n*  =======\n*\n*  SSYGS2 reduces a real symmetric-definite generalized eigenproblem\n*  to standard form.\n*\n*  If ITYPE = 1, the problem is A*x = lambda*B*x,\n*  and A is overwritten by inv(U')*A*inv(U) or inv(L)*A*inv(L')\n*\n*  If ITYPE = 2 or 3, the problem is A*B*x = lambda*x or\n*  B*A*x = lambda*x, and A is overwritten by U*A*U` or L'*A*L.\n*\n*  B must have been previously factorized as U'*U or L*L' by SPOTRF.\n*\n\n*  Arguments\n*  =========\n*\n*  ITYPE   (input) INTEGER\n*          = 1: compute inv(U')*A*inv(U) or inv(L)*A*inv(L');\n*          = 2 or 3: compute U*A*U' or L'*A*L.\n*\n*  UPLO    (input) CHARACTER*1\n*          Specifies whether the upper or lower triangular part of the\n*          symmetric matrix A is stored, and how B has been factorized.\n*          = 'U':  Upper triangular\n*          = 'L':  Lower triangular\n*\n*  N       (input) INTEGER\n*          The order of the matrices A and B.  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, if INFO = 0, the transformed matrix, stored in the\n*          same format as A.\n*\n*  LDA     (input) INTEGER\n*          The leading dimension of the array A.  LDA >= max(1,N).\n*\n*  B       (input) REAL array, dimension (LDB,N)\n*          The triangular factor from the Cholesky factorization of B,\n*          as returned by SPOTRF.\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*\n\n*  =====================================================================\n*\n\n");
      return Qnil;
    }
    if (rb_hash_aref(rblapack_options, sUsage) == Qtrue) {
      printf("%s\n", "USAGE:\n  info, a = NumRu::Lapack.ssygs2( itype, uplo, a, b, [: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_itype = argv[0];
  rblapack_uplo = argv[1];
  rblapack_a = argv[2];
  rblapack_b = argv[3];
  if (argc == 4) {
  } else if (rblapack_options != Qnil) {
  } else {
  }

  itype = NUM2INT(rblapack_itype);
  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*);
  uplo = StringValueCStr(rblapack_uplo)[0];
  if (!NA_IsNArray(rblapack_b))
    rb_raise(rb_eArgError, "b (4th argument) must be NArray");
  if (NA_RANK(rblapack_b) != 2)
    rb_raise(rb_eArgError, "rank of b (4th argument) must be %d", 2);
  ldb = NA_SHAPE0(rblapack_b);
  if (NA_SHAPE1(rblapack_b) != n)
    rb_raise(rb_eRuntimeError, "shape 1 of b must be the same as shape 1 of a");
  if (NA_TYPE(rblapack_b) != NA_SFLOAT)
    rblapack_b = na_change_type(rblapack_b, NA_SFLOAT);
  b = NA_PTR_TYPE(rblapack_b, 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__;

  ssygs2_(&itype, &uplo, &n, a, &lda, b, &ldb, &info);

  rblapack_info = INT2NUM(info);
  return rb_ary_new3(2, rblapack_info, rblapack_a);
}

void
init_lapack_ssygs2(VALUE mLapack, VALUE sH, VALUE sU, VALUE zero){
  sHelp = sH;
  sUsage = sU;
  rblapack_ZERO = zero;

  rb_define_module_function(mLapack, "ssygs2", rblapack_ssygs2, -1);
}
