diff --git a/README b/README
index 4ab73f5..0675911 100644
--- a/README
+++ b/README
@@ -39,7 +39,7 @@ integer and string.
 To install, just use
 
     make
-    
+
 This will produce a package file named "hdf5oct-*.tar.gz" .  Then
 you may either install the package with
 
@@ -48,7 +48,7 @@ you may either install the package with
 or you may start GNU Octave and install the package manually (using
 the correct file name) with the command
 
-    pkg install hdf5oct-0.2.0.tar.gz
+    pkg install hdf5oct-0.4.0.tar.gz
 
 This will put the *.oct files somewhere where Octave will find them.
 You can try running
@@ -73,4 +73,4 @@ To uninstall the package you may want to use
 - read string-array typed attributes
 
 - write more comprehensive tests instead of a few random choices. Also
-  test for error conditions.
\ No newline at end of file
+  test for error conditions.
diff --git a/h5read.cc b/h5read.cc
index f346fd5..bd7ccce 100644
--- a/h5read.cc
+++ b/h5read.cc
@@ -38,9 +38,12 @@
 #include <iostream>
 #include <algorithm>
 #include <string>
-#include "gripes.h"
+#include "errwarn.h"
 #include "file-stat.h"
 
+#define HAVE_HDF5 1
+#define HAVE_HDF5_18 1
+
 using namespace std;
 
 #if ((H5_VERS_MAJOR > 1) || (H5_VERS_MINOR >= 8))
@@ -76,7 +79,7 @@ check_vec (const octave_value& val, Matrix& mat/*out*/,
   if (error_state)
     return 0;
 
-  if (! mat.is_vector ())
+  if (! mat.isvector ())
     {
       error ("%s must be a vector", name);
       return 0;
@@ -85,7 +88,7 @@ check_vec (const octave_value& val, Matrix& mat/*out*/,
   double mind, maxd;
   if (allow_zeros)
     {
-      for (int i = 0; i < mat.nelem (); i++)
+      for (int i = 0; i < mat.length (); i++)
         {
           if (mat(i) == octave_Inf)
             mat(i) = 0;
@@ -100,7 +103,7 @@ check_vec (const octave_value& val, Matrix& mat/*out*/,
     {
       error ("%s can only contain positive integers", name);
       return 0;
-    } 
+    }
 
   return 1;
 }
@@ -148,31 +151,31 @@ the appropriate size for the given HDF5 type.\n\
 @end deftypefn")
 {
 #if ! (defined (HAVE_HDF5) && defined (HAVE_HDF5_18))
-  gripe_disabled_feature ("h5read", "HDF5 IO");
-  return octave_value_list ();
+  warn_disabled_feature ("h5read", "HDF5 IO");
+  return octave_value ();
 #else
   int nargin = args.length ();
 
   if (nargin < 2 || nargin == 3 || nargin > 6 || nargout > 1)
     {
       print_usage ();
-      return octave_value_list ();
+      return octave_value ();
     }
   if (! (args(0).is_string () && args (1).is_string ()))
     {
       print_usage ();
-      return octave_value_list ();
+      return octave_value ();
     }
 
   string filename = args(0).string_value ();
   string dsetname = args(1).string_value ();
   if (error_state)
-    return octave_value_list ();
+    return octave_value ();
 
   //open the hdf5 file
   H5File file (filename.c_str (), false);
   if (error_state)
-    return octave_value_list ();
+    return octave_value ();
 
   if (nargin < 4)
     {
@@ -183,7 +186,7 @@ the appropriate size for the given HDF5 type.\n\
     {
       Matrix start, count, stride, block;
       int err = 0;
-    
+
       err = err || ! check_vec (args(2), start, "START", false);
       start -= 1;
 
@@ -200,7 +203,7 @@ the appropriate size for the given HDF5 type.\n\
         err = err || ! check_vec (args(5), block, "BLOCK", false);
 
       if (err)
-        return octave_value_list ();
+        return octave_value ();
 
       return file.read_dset_hyperslab (dsetname.c_str (),
                                        start, count, stride, block, nargin-2);
@@ -222,8 +225,8 @@ is to read.\n\
 {
   octave_value retval;
 #if ! (defined (HAVE_HDF5) && defined (HAVE_HDF5_18))
-  gripe_disabled_feature ("h5readatt", "HDF5 IO");
-  return octave_value_list ();
+  warn_disabled_feature ("h5readatt", "HDF5 IO");
+  return octave_value ();
 #else
   int nargin = args.length ();
   if (nargin != 3)
@@ -241,13 +244,13 @@ is to read.\n\
   string objname = args(1).string_value ();
   string attname = args(2).string_value ();
   if (error_state)
-    return octave_value_list ();
-  
+    return octave_value ();
+
   //open the hdf5 file
   H5File file (filename.c_str (), false);
   if (error_state)
-    return octave_value_list ();
-        
+    return octave_value ();
+
   retval = file.read_att (objname.c_str (), attname.c_str ());
   return retval;
 
@@ -293,43 +296,43 @@ the appropriate size for the given Octave type.\n\
 @end deftypefn")
 {
 #if ! (defined (HAVE_HDF5) && defined (HAVE_HDF5_18))
-  gripe_disabled_feature ("h5write", "HDF5 IO");
-  return octave_value_list ();
+  warn_disabled_feature ("h5write", "HDF5 IO");
+  return octave_value ();
 #else
   int nargin = args.length ();
 
   if (! (nargin == 3 || nargin == 5 || nargin  == 6 || nargin == 7) || nargout != 0)
     {
       print_usage ();
-      return octave_value_list ();
+      return octave_value ();
     }
   if (! (args(0).is_string () && args(1).is_string ()))
     {
       print_usage ();
-      return octave_value_list ();
+      return octave_value ();
     }
   string filename = args(0).string_value ();
   string location = args(1).string_value ();
-  
+
   if (error_state)
-    return octave_value_list ();
-    
+    return octave_value ();
+
 
   if (nargin == 3)
     {
       //open the hdf5 file, create it if it does not exist
       H5File file (filename.c_str (), true);
       if (error_state)
-        return octave_value_list ();
+        return octave_value ();
       file.write_dset (location.c_str (),
                        args(2));
     }
-  else  
+  else
     {
       //open the hdf5 file, complain if it does not exist
       H5File file (filename.c_str (), false);
       if (error_state)
-        return octave_value_list ();
+        return octave_value ();
 
       Matrix start, count, stride, block;
       int err = 0;
@@ -350,14 +353,14 @@ the appropriate size for the given Octave type.\n\
         err = err || ! check_vec (args(6), block, "BLOCK", false);
 
       if (err)
-        return octave_value_list ();
+        return octave_value ();
 
       file.write_dset_hyperslab (location.c_str (),
                                  args(2),
                                  start, count, stride, block, nargin-3);
     }
 
-  return octave_value_list ();
+  return octave_value ();
 #endif
 }
 
@@ -373,38 +376,38 @@ the object named @var{objectname} in the HDF5 file specified by @var{filename}.\
 @end deftypefn")
 {
 #if ! (defined (HAVE_HDF5) && defined (HAVE_HDF5_18))
-  gripe_disabled_feature ("h5writeatt", "HDF5 IO");
-  return octave_value_list ();
+  warn_disabled_feature ("h5writeatt", "HDF5 IO");
+  return octave_value ();
 #else
   int nargin = args.length ();
 
   if (nargin != 4 || nargout != 0)
     {
       print_usage ();
-      return octave_value_list ();
+      return octave_value ();
     }
   if (! (args(0).is_string () && args(1).is_string () && args(2).is_string ()))
     {
       print_usage ();
-      return octave_value_list ();
+      return octave_value ();
     }
 
   string filename = args(0).string_value ();
   string location = args(1).string_value ();
   string attname = args(2).string_value ();
-  
+
   if (error_state)
-    return octave_value_list ();
-    
+    return octave_value ();
+
   //open the hdf5 file
   H5File file (filename.c_str (), false);
   if (error_state)
-    return octave_value_list ();
+    return octave_value ();
 
   file.write_att (location.c_str (), attname.c_str (),
                   args(3));
 
-  return octave_value_list ();
+  return octave_value ();
 #endif
 }
 
@@ -442,35 +445,35 @@ setting is not @sc{matlab} compatible.\n\
 @end deftypefn")
 {
 #if ! (defined (HAVE_HDF5) && defined (HAVE_HDF5_18))
-  gripe_disabled_feature("h5create", "HDF5 IO");
-  return octave_value_list ();
+  warn_disabled_feature("h5create", "HDF5 IO");
+  return octave_value ();
 #else
   int nargin = args.length ();
 
   if (! (nargin ==  3 || nargin == 5 || nargin == 7) || nargout != 0)
     {
       print_usage ();
-      return octave_value_list ();
+      return octave_value ();
     }
   if (! (args(0).is_string () && args(1).is_string ()))
     {
       print_usage ();
-      return octave_value_list ();
+      return octave_value ();
     }
   if ((nargin == 5 && ! args(3).is_string ())
       || (nargin == 7 && ! args(5).is_string ()))
     {
       print_usage ();
-      return octave_value_list ();
+      return octave_value ();
     }
   string filename = args(0).string_value ();
   string location = args(1).string_value ();
   if (error_state)
-    return octave_value_list ();
-  
+    return octave_value ();
+
   Matrix size;
   if (! check_vec (args(2), size, "SIZE", true))
-    return octave_value_list ();
+    return octave_value ();
 
 
   // loop over the key-value pairs and see what is given
@@ -484,7 +487,7 @@ setting is not @sc{matlab} compatible.\n\
           if (error_state)
             {
               error ("Datatype argument must be a string");
-              return octave_value_list ();
+              return octave_value ();
             }
         }
       else if (args(i).string_value () == "ChunkSize")
@@ -494,31 +497,31 @@ setting is not @sc{matlab} compatible.\n\
 	      if(args(i+1).string_value () != "auto")
 		{
 		  error ("ChunkSize argument must be either a vector, or the string 'auto'.");
-		  return octave_value_list ();
+		  return octave_value ();
 		}
 	      chunksize = args(2).matrix_value ();
 	      chunksize(0) = 0;
 
 	    }
           else if (! check_vec (args(i+1), chunksize, "ChunkSize", false))
-            return octave_value_list ();
+            return octave_value ();
         }
       else
         {
           error ("unknown parameter name %s", args(i).string_value ().c_str ());
-          return octave_value_list ();
+          return octave_value ();
         }
     }
 
-  
-  
+
+
   //open the hdf5 file
   H5File file (filename.c_str (), true);
   if (error_state)
-    return octave_value_list ();
+    return octave_value ();
   file.create_dset (location.c_str (), size, datatype.c_str (), chunksize);
-  
-  return octave_value_list ();
+
+  return octave_value ();
 #endif
 }
 
@@ -541,36 +544,36 @@ Note that this function is not @sc{matlab} compliant.\n\
 @end deftypefn")
 {
 #if ! (defined (HAVE_HDF5) && defined (HAVE_HDF5_18))
-  gripe_disabled_feature("h5delete", "HDF5 IO");
-  return octave_value_list ();
+  warn_disabled_feature("h5delete", "HDF5 IO");
+  return octave_value ();
 #else
   int nargin = args.length ();
 
   if (! (nargin ==  2 || nargin == 3) || nargout != 0)
     {
       print_usage ();
-      return octave_value_list ();
+      return octave_value ();
     }
   if (! (args(0).is_string () && args(1).is_string ()))
     {
       print_usage ();
-      return octave_value_list ();
+      return octave_value ();
     }
   if (nargin == 3 && ! args(2).is_string ())
     {
       print_usage ();
-      return octave_value_list ();
+      return octave_value ();
     }
-  
+
   string filename = args(0).string_value ();
   string location = args(1).string_value ();
   if (error_state)
-    return octave_value_list ();
+    return octave_value ();
 
   //open the hdf5 file
   H5File file (filename.c_str (), true);
   if (error_state)
-    return octave_value_list ();
+    return octave_value ();
   if (nargin == 2)
     file.delete_link (location.c_str ());
   else if (nargin == 3)
@@ -579,8 +582,8 @@ Note that this function is not @sc{matlab} compliant.\n\
       if(!error_state)
 	file.delete_att (location.c_str (), attname.c_str ());
     }
-  
-  return octave_value_list ();
+
+  return octave_value ();
 #endif
 }
 
@@ -594,7 +597,7 @@ H5File::H5File (const char *filename, const bool create_if_nonexisting)
   //suppress hdf5 error output
   H5Eset_auto (H5E_DEFAULT,0,0);
 
-  file_stat fs (filename);
+  octave::sys::file_stat fs (filename);
   if (! fs.exists () && create_if_nonexisting)
     file = H5Fcreate (filename, H5F_ACC_TRUNC, H5P_DEFAULT, H5P_DEFAULT);
   else if (! fs.exists () && ! create_if_nonexisting)
@@ -625,7 +628,7 @@ H5File::~H5File ()
 
   if (H5Iis_valid (dset_id))
     H5Dclose (dset_id);
-  
+
   if (H5Iis_valid (att_id))
     H5Aclose (att_id);
 
@@ -634,7 +637,7 @@ H5File::~H5File ()
 
   if (H5Iis_valid (type_id))
     H5Tclose (type_id);
-  
+
   if (H5Iis_valid (mem_type_id))
     H5Tclose (mem_type_id);
 
@@ -711,7 +714,7 @@ H5File::open_dset (const char *dsetname)
       error ("Error determining current dimensions and maximum size of dataset %s", dsetname);
       return -1;
     }
-  
+
   return 0;
 }
 
@@ -719,7 +722,7 @@ octave_value
 H5File::read_dset_complete (const char *dsetname)
 {
   if (open_dset (dsetname) < 0)
-    return octave_value_list ();
+    return octave_value ();
 
   mat_dims.resize (max (rank, 2));
   // .resize(1) still leaves mat_dims with a length of 2 for some reason, so
@@ -732,7 +735,7 @@ H5File::read_dset_complete (const char *dsetname)
   if (H5Sselect_all (dspace_id) < 0)
     {
       error ("Error selecting complete dataset %s", dsetname);
-      return octave_value_list ();
+      return octave_value ();
     }
 
   octave_value retval = read_dset ();
@@ -746,43 +749,43 @@ H5File::read_dset_hyperslab (const char *dsetname,
                              int nargin)
 {
   if (open_dset (dsetname) < 0)
-    return octave_value_list ();
+    return octave_value ();
 
-  if (rank == 0 && ! (start.is_empty () && count.is_empty ()
-                      && stride.is_empty () && block.is_empty ()))
+  if (rank == 0 && ! (start.isempty () && count.isempty ()
+                      && stride.isempty () && block.isempty ()))
     {
       error ("Cannot specify hyperslab for scalar datasets (rank 0)");
-      return octave_value_list ();
+      return octave_value ();
     }
 
-  if (start.nelem () != rank)
+  if (start.length () != rank)
     {
       error ("start must be a vector of length %d, the dataset rank", rank);
-      return octave_value_list ();
+      return octave_value ();
     }
-  if (count.nelem () != rank)
+  if (count.length () != rank)
     {
       error ("count must be a vector of length %d, the dataset rank", rank);
-      return octave_value_list ();
+      return octave_value ();
     }
-  
+
   Matrix _stride = stride;
   if (nargin < 3)
     _stride = Matrix (dim_vector(1, rank), 1);
-  if (_stride.nelem () != rank)
+  if (_stride.length () != rank)
     {
       error ("stride must be a vector of length %d, the dataset rank", rank);
-      return octave_value_list ();
+      return octave_value ();
     }
   Matrix _block = block;
   if (nargin < 4)
     _block = Matrix (dim_vector(1, rank), 1);
-  if (_block.nelem () != rank)
+  if (_block.length () != rank)
     {
       error ("block must be a vector of length %d, the dataset rank", rank);
-      return octave_value_list ();
+      return octave_value ();
     }
-  
+
   // .resize(1) still leaves mat_dims with a length of 2 for some reason, so
   // we need at least 2 filled
   mat_dims.resize (max (rank, 2));
@@ -795,7 +798,7 @@ H5File::read_dset_hyperslab (const char *dsetname,
         {
           error ("In dimension %d, requested stride %d smaller than block size %d",
                  i+1, (int)_stride(i), (int)_block(i));
-          return octave_value_list ();
+          return octave_value ();
         }
       if (_count(i) == 0)
         {
@@ -804,13 +807,13 @@ H5File::read_dset_hyperslab (const char *dsetname,
           _count(i) = (h5_dims[rank-i-1] - start(i) - _block(i)) / _stride(i) + 1;
         }
       mat_dims(i) = _count(i)*_block(i);
-      int end = start(i) + _stride(i)*(_count(i)-1) + _block(i); // exclusive
+      unsigned int end = start(i) + _stride(i)*(_count(i)-1) + _block(i); // exclusive
       if (h5_dims[rank-i-1] < end)
         {
           error ("In dimension %d, dataset only has %d elements, but at least %d"
                  " are required for requested hyperslab", i+1, (int)h5_dims[rank-i-1],
                  end);
-          return octave_value_list ();
+          return octave_value ();
         }
     }
 
@@ -829,7 +832,7 @@ H5File::read_dset_hyperslab (const char *dsetname,
   free (hblock);
 
   if (sel_result < 0)
-    return octave_value_list ();
+    return octave_value ();
 
   octave_value retval = read_dset ();
   return retval;
@@ -857,20 +860,20 @@ H5File::read_dset ()
       if (H5Sselect_valid (dspace_id) <= 0)                             \
         {                                                               \
           error ("selected dataspace is not valid");                    \
-          return octave_value_list ();                                  \
+          return octave_value ();                                  \
         }                                                               \
                                                                         \
-      int mdc_nelem = -1;                                               \
-      size_t rdcc_nelem = -1;                                           \
+      int mdc_length = -1;                                               \
+      size_t rdcc_length = -1;                                           \
       size_t rdcc_nbytes = -1;                                          \
       double rdcc_w0 = -1;                                              \
-      if (H5Pget_cache (H5Fget_access_plist (file), &mdc_nelem,         \
-                        &rdcc_nelem, &rdcc_nbytes, &rdcc_w0 ) < 0)      \
+      if (H5Pget_cache (H5Fget_access_plist (file), &mdc_length,         \
+                        &rdcc_length, &rdcc_nbytes, &rdcc_w0 ) < 0)      \
         {                                                               \
           error ("could not determine raw data chunk cache parameters."); \
-          return octave_value_list ();                                  \
+          return octave_value ();                                  \
         }                                                               \
-      /*cout << "cache params:" << rdcc_nelem << "," << rdcc_nbytes << endl;*/ \
+      /*cout << "cache params:" << rdcc_length << "," << rdcc_nbytes << endl;*/ \
       herr_t read_result = H5Dread (dset_id,                            \
                                     type,                               \
                                     H5S_ALL, dspace_id,                 \
@@ -878,11 +881,11 @@ H5File::read_dset ()
       if (read_result < 0)                                              \
         {                                                               \
           error ("error when reading dataset");                         \
-          return octave_value_list ();                                  \
+          return octave_value ();                                  \
         }                                                               \
       retval = octave_value (ret)
       // macro end
-      
+
       HDF5_READ_DATA (type_id);
     }
   else if (H5Tget_class (type_id) == H5T_INTEGER)
@@ -959,7 +962,7 @@ H5File::read_dset ()
       HDF5_READ_DATA (H5T_NATIVE_DOUBLE);
     }
   H5Tclose (complex_type_id);
-  
+
   return retval;
 }
 
@@ -997,12 +1000,12 @@ H5File::write_dset (const char *dsetname,
 
   herr_t status;
   // find the right type
-  if (ov_data.is_complex_type ())
+  if (ov_data.iscomplex ())
     {
       //check if the data set already exists. if it does, open it,
       //otherwise, create it.  Furthermore check if the datatype is
       //compliant with given octave data.
-  
+
 #define OPEN_AND_WRITE if (H5Lexists (file,dsetname,H5P_DEFAULT))       \
         {                                                               \
           if (open_dset (dsetname) < 0)                                 \
@@ -1018,12 +1021,12 @@ H5File::write_dset (const char *dsetname,
       status = H5Dwrite (dset_id, type_id,                              \
                          H5S_ALL, H5S_ALL, H5P_DEFAULT,                 \
                          data.fortran_vec ())
-  
+
       type_id = hdf5_make_complex_type (H5T_NATIVE_DOUBLE);
       ComplexNDArray data = ov_data.complex_array_value ();
       OPEN_AND_WRITE;
     }
-  else if (ov_data.is_integer_type ())
+  else if (ov_data.isinteger ())
     {
       if (ov_data.is_uint64_type ())
         {
@@ -1079,7 +1082,7 @@ H5File::write_dset (const char *dsetname,
           type_id = H5Tcopy (H5T_NATIVE_INT);
           OPEN_AND_WRITE;
         }
-      
+
     }
   else if (ov_data.is_single_type ())
     {
@@ -1115,19 +1118,19 @@ H5File::write_dset_hyperslab (const char *dsetname,
     return;
 
   // check if the given hyperslab settings are reasonable
-  if (rank == 0 && ! (start.is_empty () && count.is_empty ()
-                      && stride.is_empty () && block.is_empty ()))
+  if (rank == 0 && ! (start.isempty () && count.isempty ()
+                      && stride.isempty () && block.isempty ()))
     {
       error ("Cannot specify hyperslab for scalar datasets (rank 0)");
       return;
     }
 
-  if (start.nelem () != rank)
+  if (start.length () != rank)
     {
       error ("start must be a vector of length %d, the dataset rank", rank);
       return;
     }
-  if (count.nelem () != rank)
+  if (count.length () != rank)
     {
       error ("count must be a vector of length %d, the dataset rank", rank);
       return;
@@ -1135,7 +1138,7 @@ H5File::write_dset_hyperslab (const char *dsetname,
   Matrix _stride = stride;
   if (nargin < 3)
     _stride = Matrix (dim_vector(1, rank), 1);
-  if (_stride.nelem () != rank)
+  if (_stride.length () != rank)
     {
       error ("stride must be a vector of length %d, the dataset rank", rank);
       return;
@@ -1143,7 +1146,7 @@ H5File::write_dset_hyperslab (const char *dsetname,
   Matrix _block = block;
   if (nargin < 4)
     _block = Matrix (dim_vector(1, rank), 1);
-  if (_block.nelem () != rank)
+  if (_block.length () != rank)
     {
       error ("block must be a vector of length %d, the dataset rank", rank);
       return;
@@ -1162,7 +1165,7 @@ H5File::write_dset_hyperslab (const char *dsetname,
 
       // A count value 0 is not allowed when writing data.
 
-      int end = start(i) + _stride(i)*(count(i)-1) + _block(i); // exclusive
+      unsigned int end = start(i) + _stride(i)*(count(i)-1) + _block(i); // exclusive
       if (h5_maxdims[rank-i-1] < end)
         {
           error ("In dimension %d, the dataset %s may have at max. only %d elements,"
@@ -1182,7 +1185,7 @@ H5File::write_dset_hyperslab (const char *dsetname,
   hsize_t *hcount = alloc_hsize (count, ALLOC_HSIZE_DEFAULT, true);
   hsize_t *hblock = alloc_hsize (_block, ALLOC_HSIZE_DEFAULT, true);
   // TODO check these (and hmem) for NULLs
-  
+
   // make the current size of the dataset bigger
   H5Sclose (dspace_id);
   if (H5Dset_extent (dset_id, h5_dims) < 0)
@@ -1209,7 +1212,7 @@ H5File::write_dset_hyperslab (const char *dsetname,
       error ("error when selecting the hyperslab of dataset %s to write to", dsetname);
       return;
     }
-  
+
   hsize_t *hmem = alloc_hsize (data.dims (), ALLOC_HSIZE_DEFAULT, false);
   hid_t memspace_id = H5Screate_simple (rank, hmem, hmem);
   if (memspace_id < 0)
@@ -1218,7 +1221,7 @@ H5File::write_dset_hyperslab (const char *dsetname,
       return;
     }
   free (hmem);
-  
+
   herr_t status = H5Dwrite (dset_id, H5T_NATIVE_DOUBLE,
                             memspace_id, dspace_id, H5P_DEFAULT,
                             data.fortran_vec ());
@@ -1227,7 +1230,7 @@ H5File::write_dset_hyperslab (const char *dsetname,
       error ("error when writing the dataset %s", dsetname);
       return;
     }
-  
+
 }
 
 
@@ -1268,7 +1271,7 @@ H5File::read_att (const char *objname, const char *attname)
     {
       // Size of each string:
       size_t size = H5Tget_size (type);
-      // to read an array of strings (for future work): 
+      // to read an array of strings (for future work):
       //totsize = size*sdim[0]*sdim[1];
       // to read a single string:
       size_t totsize = size;
@@ -1284,7 +1287,7 @@ H5File::read_att (const char *objname, const char *attname)
   else if (H5Tget_class (type)==H5T_INTEGER)
     {
       // Integer attributes are casted to floating point octave values
-    
+
       double value[numVal];
       if (H5Tget_size (type)==sizeof (int))
         {
@@ -1307,7 +1310,7 @@ H5File::read_att (const char *objname, const char *attname)
       for (size_t n=0;n<numVal;++n)
         mat(n)=value[n];
       retval = octave_value (mat);
-    
+
     }
   else if (H5Tget_class (type) == H5T_FLOAT)
     {
@@ -1349,7 +1352,7 @@ cannot handle size of type");
       error ("h5readatt: attribute type not supported");
       return retval;
     }
-  
+
   return retval;
 }
 
@@ -1357,16 +1360,12 @@ void
 H5File::write_att (const char *location, const char *attname,
                    const octave_value& attvalue)
 {
-  hsize_t *dims;
   if (attvalue.is_scalar_type () || attvalue.is_string ())
     dspace_id = H5Screate (H5S_SCALAR);
   else if (attvalue.is_matrix_type ())
     {
       error ("matrix type attributes are not yet supported.");
       return;
-      // dims = alloc_hsize (attvalue.dims (), ALLOC_HSIZE_DEFAULT, true);
-      // dspace_id = H5Screate_simple (attvalue.dims ().length (), dims, NULL);
-      // free (dims);
     }
   else
     {
@@ -1386,7 +1385,7 @@ H5File::write_att (const char *location, const char *attname,
       error ("the specified HDF5 object %s could not be opened", location);
       return;
     }
-  
+
   //Check if an attribute with the given name exists already at that
   //object and if yes delete it.
   htri_t exists = H5Aexists (obj_id, attname);
@@ -1414,10 +1413,10 @@ H5File::write_att (const char *location, const char *attname,
       H5Tset_size (type_id, attvalue.string_value ().length ());
       H5Tset_strpad (type_id,H5T_STR_NULLTERM);
       mem_type_id = H5Tcopy (type_id);
-      
+
       buf = (void *) attvalue.string_value ().c_str ();
     }
-  else if (attvalue.is_integer_type ())
+  else if (attvalue.isinteger ())
     {
       //type_id = H5Tcopy (H5T_STD_I64LE); //cannot read this back in then, don't know why
       type_id = H5Tcopy (H5T_NATIVE_INT);
@@ -1425,14 +1424,14 @@ H5File::write_att (const char *location, const char *attname,
       attval_int = attvalue.int_value ();
       buf = (void *) &attval_int;
     }
-  else if (attvalue.is_real_type ())
+  else if (attvalue.isreal ())
     {
       type_id = H5Tcopy (H5T_NATIVE_DOUBLE);
       mem_type_id = H5Tcopy (H5T_NATIVE_DOUBLE);
       attval_double = attvalue.double_value ();
       buf = (void *) &attval_double;
     }
-  else if (attvalue.is_complex_type ())
+  else if (attvalue.iscomplex ())
     {
       error ("complex values are not supported by the HDF5 format. \
 You have to save real and imag part separately.");
@@ -1525,37 +1524,37 @@ H5File::create_dset (const char *location, const Matrix& size,
   hsize_t *dims = alloc_hsize (size, ALLOC_HSIZE_INF_TO_ZERO, true);
   // and produce unlimited maximum extent for..
   hsize_t *maxdims = alloc_hsize (size, ALLOC_HSIZE_INFZERO_TO_UNLIMITED, true);
-  dspace_id = H5Screate_simple (size.nelem (), dims, maxdims);
+  dspace_id = H5Screate_simple (size.length (), dims, maxdims);
   free (dims);
   free (maxdims);
 
-  if (any_int_leq_zero (size) && chunksize.is_empty ())
+  if (any_int_leq_zero (size) && chunksize.isempty ())
     {
       error ("If the size argument contains an Inf or zero element, then ChunkSize must be specified.");
       return;
     }
   // get a dataset creation property list
   hid_t crp_list = H5Pcreate (H5P_DATASET_CREATE);
-  if (! chunksize.is_empty ())
+  if (! chunksize.isempty ())
     {
       // a dataset with an unlimited dimension must be chunked.
       if (chunksize(0) == 0)
 	chunksize = get_auto_chunksize(size, typesize);
-      
+
       hsize_t *dims_chunk = alloc_hsize (chunksize, ALLOC_HSIZE_DEFAULT, true);
       if (H5Pset_layout (crp_list, H5D_CHUNKED) < 0)
         {
           error ("Could not set chunked layout of %s", location);
           return;
         }
-      if (H5Pset_chunk (crp_list, size.nelem (), dims_chunk) < 0)
+      if (H5Pset_chunk (crp_list, size.length (), dims_chunk) < 0)
         {
           error ("Could not set chunk size of %s", location);
           return;
         }
       free (dims_chunk);
     }
-  
+
   dset_id = H5Dcreate (file, location, type_id, dspace_id,
                        H5P_DEFAULT, crp_list, H5P_DEFAULT);
   if (dset_id < 0)
@@ -1595,7 +1594,7 @@ Matrix
 H5File::get_auto_chunksize(const Matrix& dset_shape, int typesize)
 {
   // This function originally stems from the h5py project.
-  
+
   // Guess an appropriate chunk layout for a dataset, given its shape and
   // the size of each element in bytes. Will allocate chunks only as large
   // as MAX_SIZE. Chunks are generally close to some power-of-2 fraction of
@@ -1634,10 +1633,10 @@ H5File::get_auto_chunksize(const Matrix& dset_shape, int typesize)
 	   abs(chunk_bytes-target_size)/target_size < 0.5) &&
 	  chunk_bytes < CHUNK_MAX)
 	break;
-      
+
       if (chunksize.prod ()(0) == 1)
 	break; // Element size larger than CHUNK_MAX
-      
+
       chunksize(idx%ndims) = ceil(chunksize(idx%ndims) / 2.0);
       idx++;
     }
diff --git a/package/DESCRIPTION b/package/DESCRIPTION
index b27cc8b..bed7b10 100644
--- a/package/DESCRIPTION
+++ b/package/DESCRIPTION
@@ -1,5 +1,5 @@
 Name: hdf5oct
-Version: 0.2.0
+Version: 0.4.0
 Date: 2015-10-02
 Author: Tom Mullins, Anton Starikov, Thorsten Liebig, Stefan Großhauser
 Maintainer: Stefan Großhauser <Stefan.Grosshauser@uni-bayreuth.de>
@@ -8,4 +8,4 @@ Title: a HDF5 wrapper for GNU Octave
 Url: https://github.com/stegro/hdf5oct
 Description: Currently this package provides a rather small number of
  function, in order to access datasets and attributes of HDF5 files.
-License: LGPLv3+
\ No newline at end of file
+License: LGPLv3+