diff --git a/lib/AsciiFile.cpp b/lib/AsciiFile.cpp
index 70466a7..7be756c 100644
--- a/lib/AsciiFile.cpp
+++ b/lib/AsciiFile.cpp
@@ -71,7 +71,22 @@ void AsciiFile::save(const DMat &m, const std::string &name)
     fileStream_.precision(defaultPrec);
 }
 
-void AsciiFile::save(const DMatSample &s, const std::string &name)
+void AsciiFile::save(const DSample &ds, const std::string &name)
+{
+    if (name.empty())
+    {
+        LATAN_ERROR(Io, "trying to save data with an empty name");
+    }
+    
+    checkWritability();
+    isParsed_ = false;
+    fileStream_ << "#L latan_begin rs_sample " << name << endl;
+    fileStream_ << ds.size() << endl;
+    save(ds.matrix(), name + "_data");
+    fileStream_ << "#L latan_end rs_sample " << endl;
+}
+
+void AsciiFile::save(const DMatSample &ms, const std::string &name)
 {
     if (name.empty())
     {
@@ -81,11 +96,11 @@ void AsciiFile::save(const DMatSample &s, const std::string &name)
     checkWritability();
     isParsed_ = false;
     fileStream_ << "#L latan_begin rs_sample " << name << endl;
-    fileStream_ << s.size() << endl;
-    save(s[central], name + "_C");
-    for (Index i = 0; i < s.size(); ++i)
+    fileStream_ << ms.size() << endl;
+    save(ms[central], name + "_C");
+    for (Index i = 0; i < ms.size(); ++i)
     {
-        save(s[i], name + "_S_" + strFrom(i));
+        save(ms[i], name + "_S_" + strFrom(i));
     }
     fileStream_ << "#L latan_end rs_sample " << endl;
 }
diff --git a/lib/AsciiFile.hpp b/lib/AsciiFile.hpp
index 4385e02..e160dee 100644
--- a/lib/AsciiFile.hpp
+++ b/lib/AsciiFile.hpp
@@ -49,6 +49,7 @@ public:
         std::string first;
         // parsing buffers
         RandGenState       stateBuf;
+        DSample            dSampleBuf;
         DMatSample         dMatSampleBuf;
         std::queue<DMat>   dMatQueue;
         std::queue<double> doubleQueue;
@@ -66,7 +67,8 @@ public:
     virtual ~AsciiFile(void);
     // access
     virtual void save(const DMat &m, const std::string &name);
-    virtual void save(const DMatSample &s, const std::string &name);
+    virtual void save(const DSample &ds, const std::string &name);
+    virtual void save(const DMatSample &ms, const std::string &name);
     virtual void save(const RandGenState &state, const std::string &name);
     // read first name
     virtual std::string getFirstName(void);
diff --git a/lib/AsciiParser.ypp b/lib/AsciiParser.ypp
index 05f174b..ca4cd64 100644
--- a/lib/AsciiParser.ypp
+++ b/lib/AsciiParser.ypp
@@ -69,7 +69,7 @@
 %token <val_str>    ID
 %token OPEN CLOSE MAT SAMPLE RG_STATE
 
-%type <val_str> mat sample rg_state
+%type <val_str> mat matsample dsample rg_state
 
 %{
 	int _Ascii_lex(YYSTYPE* lvalp, YYLTYPE* llocp, void* scanner);
@@ -101,7 +101,12 @@ data:
         (*state->data)[$1].reset(new DMat(state->dMatQueue.front()));
         state->dMatQueue.pop();
     }
-    | sample
+    | dsample
+    {
+        TEST_FIRST($1);
+        (*state->data)[$1].reset(new DSample(state->dSampleBuf));
+    }
+    | matsample
     {
         TEST_FIRST($1);
         (*state->data)[$1].reset(new DMatSample(state->dMatSampleBuf));
@@ -138,15 +143,37 @@ mat:
     }
     ;
 
-sample:
-      OPEN SAMPLE ID INT mats CLOSE SAMPLE
+dsample:
+      OPEN SAMPLE ID INT mat CLOSE SAMPLE
+    {
+        const unsigned int nSample = $4, os = DMatSample::offset;
+        
+        DMat &m = state->dMatQueue.front();
+        if (m.rows() != nSample + os)
+        {
+            LATAN_ERROR(Size, "double sample '" + *state->streamName + ":"
+                        + $3 + "' has a wrong size");
+        }
+        if (m.cols() != 1)
+        {
+            LATAN_ERROR(Size, "double sample '" + *state->streamName + ":"
+                        + $3 + "' is not stored as a column vector");
+        }
+        state->dSampleBuf = m.array();
+        state->dMatQueue.pop();
+        strcpy($$, $3);
+    }
+    ;
+
+matsample:
+      OPEN SAMPLE ID INT mat mats CLOSE SAMPLE
     {
         const unsigned int nSample = $4, os = DMatSample::offset;
         
         if (state->dMatQueue.size() != nSample + os)
         {
-            LATAN_ERROR(Size, "sample '" + *state->streamName + ":" + $3 +
-                        "' has a wrong size");
+            LATAN_ERROR(Size, "matrix sample '" + *state->streamName + ":"
+                        + $3 + "' has a wrong size");
         }
         state->dMatSampleBuf.resize(nSample);
         state->dMatSampleBuf[central] = state->dMatQueue.front();
@@ -158,6 +185,7 @@ sample:
         }
         strcpy($$, $3);
     }
+    ;
 
 rg_state:
       OPEN RG_STATE ID ints CLOSE RG_STATE
diff --git a/lib/File.cpp b/lib/File.cpp
index 7c97a14..0f770e2 100644
--- a/lib/File.cpp
+++ b/lib/File.cpp
@@ -52,10 +52,6 @@ unsigned int File::getMode(void) const
 // internal functions //////////////////////////////////////////////////////////
 void File::deleteData(void)
 {
-    for (auto &i : data_)
-    {
-        i.second.reset();
-    }
     data_.clear();
 }
 
diff --git a/lib/File.hpp b/lib/File.hpp
index d180248..de1d1bb 100644
--- a/lib/File.hpp
+++ b/lib/File.hpp
@@ -61,7 +61,8 @@ public:
     template <typename IoT>
     const IoT &  read(const std::string &name = "");
     virtual void save(const DMat &m, const std::string &name)             = 0;
-    virtual void save(const DMatSample &state, const std::string &name)   = 0;
+    virtual void save(const DSample &ds, const std::string &name)         = 0;
+    virtual void save(const DMatSample &ms, const std::string &name)      = 0;
     virtual void save(const RandGenState &state, const std::string &name) = 0;
     // read first name
     virtual std::string getFirstName(void) = 0;
diff --git a/lib/Hdf5File.cpp b/lib/Hdf5File.cpp
index ca2a079..5ea6b10 100644
--- a/lib/Hdf5File.cpp
+++ b/lib/Hdf5File.cpp
@@ -30,6 +30,7 @@ using namespace H5NS;
 constexpr unsigned int maxGroupNameSize = 1024u;
 
 const short dMatType       = static_cast<short>(IoObject::IoType::dMat);
+const short dSampleType    = static_cast<short>(IoObject::IoType::dSample);
 const short dMatSampleType = static_cast<short>(IoObject::IoType::dMatSample);
 const short rgStateType    = static_cast<short>(IoObject::IoType::rgState);
 
@@ -65,7 +66,6 @@ void Hdf5File::save(const DMat &m, const string &name)
     hsize_t   dim[2]  = {static_cast<hsize_t>(m.rows()),
                          static_cast<hsize_t>(m.cols())};
     hsize_t   attrDim = 1;
-
     DataSpace dataSpace(2, dim), attrSpace(1, &attrDim);
 
     group = h5File_->createGroup(name.c_str() + nameOffset(name));
@@ -75,7 +75,31 @@ void Hdf5File::save(const DMat &m, const string &name)
     dataset.write(m.data(), PredType::NATIVE_DOUBLE);
 }
 
-void Hdf5File::save(const DMatSample &sample, const string &name)
+void Hdf5File::save(const DSample &ds, const string &name)
+{
+    if (name.empty())
+    {
+        LATAN_ERROR(Io, "trying to save data with an empty name");
+    }
+    
+    Group          group;
+    Attribute      attr;
+    DataSet        dataset;
+    hsize_t        dim     = static_cast<hsize_t>(ds.size() + 1);
+    hsize_t        attrDim = 1;
+    DataSpace      dataSpace(1, &dim), attrSpace(1, &attrDim);
+    const long int nSample = ds.size();
+    
+    group = h5File_->createGroup(name.c_str() + nameOffset(name));
+    attr  = group.createAttribute("type", PredType::NATIVE_SHORT, attrSpace);
+    attr.write(PredType::NATIVE_SHORT, &dSampleType);
+    attr  = group.createAttribute("nSample", PredType::NATIVE_LONG, attrSpace);
+    attr.write(PredType::NATIVE_LONG, &nSample);
+    dataset = group.createDataSet("data", PredType::NATIVE_DOUBLE, dataSpace);
+    dataset.write(ds.data(), PredType::NATIVE_DOUBLE);
+}
+
+void Hdf5File::save(const DMatSample &ms, const string &name)
 {
     if (name.empty())
     {
@@ -85,11 +109,11 @@ void Hdf5File::save(const DMatSample &sample, const string &name)
     Group          group;
     Attribute      attr;
     DataSet        dataset;
-    hsize_t        dim[2]  = {static_cast<hsize_t>(sample[central].rows()),
-                              static_cast<hsize_t>(sample[central].cols())};
+    hsize_t        dim[2]  = {static_cast<hsize_t>(ms[central].rows()),
+                              static_cast<hsize_t>(ms[central].cols())};
     hsize_t        attrDim = 1;
     DataSpace      dataSpace(2, dim), attrSpace(1, &attrDim);
-    const long int nSample = sample.size();
+    const long int nSample = ms.size();
     string         datasetName;
 
     group = h5File_->createGroup(name.c_str() + nameOffset(name));
@@ -97,13 +121,13 @@ void Hdf5File::save(const DMatSample &sample, const string &name)
     attr.write(PredType::NATIVE_SHORT, &dMatSampleType);
     attr  = group.createAttribute("nSample", PredType::NATIVE_LONG, attrSpace);
     attr.write(PredType::NATIVE_LONG, &nSample);
-    FOR_STAT_ARRAY(sample, s)
+    FOR_STAT_ARRAY(ms, s)
     {
         datasetName = (s == central) ? "data_C" : ("data_S_" + strFrom(s));
         dataset     = group.createDataSet(datasetName.c_str(),
                                           PredType::NATIVE_DOUBLE,
                                           dataSpace);
-        dataset.write(sample[s].data(), PredType::NATIVE_DOUBLE);
+        dataset.write(ms[s].data(), PredType::NATIVE_DOUBLE);
     }
 }
 
@@ -253,6 +277,17 @@ void Hdf5File::load(DMat &m, const DataSet &d)
     d.read(m.data(), PredType::NATIVE_DOUBLE);
 }
 
+void Hdf5File::load(DSample &ds, const DataSet &d)
+{
+    DataSpace dataspace;
+    hsize_t   dim[1];
+    
+    dataspace = d.getSpace();
+    dataspace.getSimpleExtentDims(dim);
+    ds.resize(dim[0] - 1);
+    d.read(ds.data(), PredType::NATIVE_DOUBLE);
+}
+
 void Hdf5File::load(RandGenState &state, const DataSet &d)
 {
     DataSpace dataspace;
@@ -296,6 +331,15 @@ string Hdf5File::load(const string &name)
                 load(*pt, dataset);
                 break;
             }
+            case IoObject::IoType::dSample:
+            {
+                DSample *pt = new DSample;
+                
+                data_[groupName].reset(pt);
+                dataset = group.openDataSet("data");
+                load(*pt, dataset);
+                break;
+            }
             case IoObject::IoType::dMatSample:
             {
                 DMatSample *pt = new DMatSample;
diff --git a/lib/Hdf5File.hpp b/lib/Hdf5File.hpp
index 670b0b6..dc2f6bf 100644
--- a/lib/Hdf5File.hpp
+++ b/lib/Hdf5File.hpp
@@ -46,7 +46,8 @@ public:
     virtual ~Hdf5File(void);
     // access
     virtual void save(const DMat &m, const std::string &name);
-    virtual void save(const DMatSample &s, const std::string &name);
+    virtual void save(const DSample &ds, const std::string &name);
+    virtual void save(const DMatSample &ms, const std::string &name);
     virtual void save(const RandGenState &state, const std::string &name);
     // read first name
     virtual std::string getFirstName(void);
@@ -60,6 +61,7 @@ private:
             std::string getFirstGroupName(void);
     virtual std::string load(const std::string &name = "");
                    void load(DMat &m, const H5NS::DataSet &d);
+                   void load(DSample &ds, const H5NS::DataSet &d);
                    void load(DMatSample &s, const H5NS::DataSet &d);
                    void load(RandGenState &state, const H5NS::DataSet &d);
     // check name for forbidden characters
diff --git a/lib/IoObject.hpp b/lib/IoObject.hpp
index 922b343..358baef 100644
--- a/lib/IoObject.hpp
+++ b/lib/IoObject.hpp
@@ -30,12 +30,14 @@ BEGIN_LATAN_NAMESPACE
 class IoObject
 {
 public:
+    // conserve order for datafile retro-compatibility!
     enum class IoType: short int
     {
         noType     = 0,
         dMat       = 1,
         dMatSample = 2,
-        rgState    = 3
+        rgState    = 3,
+        dSample    = 4
     };
 public:
     // destructor
diff --git a/lib/Makefile.am b/lib/Makefile.am
index fcd46f0..9b877a9 100644
--- a/lib/Makefile.am
+++ b/lib/Makefile.am
@@ -37,13 +37,13 @@ libLatAnalyze_la_SOURCES = \
     MathInterpreter.cpp    \
     MathParser.ypp         \
     MathLexer.lpp          \
-    MatSample.cpp          \
     Minimizer.cpp          \
     Model.cpp              \
     Plot.cpp               \
     RandGen.cpp            \
     RootFinder.cpp         \
     Solver.cpp             \
+    StatArray.cpp          \
     TabFunction.cpp        \
     XYSampleData.cpp       \
     XYStatData.cpp         \
diff --git a/lib/MatSample.hpp b/lib/MatSample.hpp
index c93907e..3cd6609 100644
--- a/lib/MatSample.hpp
+++ b/lib/MatSample.hpp
@@ -35,7 +35,7 @@ BEGIN_LATAN_NAMESPACE
                                     std::placeholders::_1, x))
 
 template <typename T>
-class MatSample: public Sample<Mat<T>>, public IoObject
+class MatSample: public Sample<Mat<T>>
 {
 public:
     // block type template
@@ -104,9 +104,6 @@ public:
                      const Index nCol);
     // resize all matrices
     void resizeMat(const Index nRow, const Index nCol);
-    // IO type
-    virtual IoType getType(void) const;
-
 };
 
 // non-member operators
@@ -383,12 +380,6 @@ void MatSample<T>::resizeMat(const Index nRow, const Index nCol)
     }
 }
 
-// IO type /////////////////////////////////////////////////////////////////////
-template <typename T>
-IoObject::IoType MatSample<T>::getType(void) const
-{
-    return IoType::noType;
-}
 
 END_LATAN_NAMESPACE
 
diff --git a/lib/MatSample.cpp b/lib/StatArray.cpp
similarity index 85%
rename from lib/MatSample.cpp
rename to lib/StatArray.cpp
index 94b8444..0feb1d4 100644
--- a/lib/MatSample.cpp
+++ b/lib/StatArray.cpp
@@ -1,5 +1,5 @@
 /*
- * MatSample.cpp, part of LatAnalyze 3
+ * StatArray.cpp, part of LatAnalyze 3
  *
  * Copyright (C) 2013 - 2015 Antonin Portelli
  *
@@ -17,7 +17,7 @@
  * along with LatAnalyze 3.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-#include <LatAnalyze/MatSample.hpp>
+#include <LatAnalyze/StatArray.hpp>
 #include <LatAnalyze/includes.hpp>
 
 using namespace std;
@@ -25,7 +25,7 @@ using namespace std;
 namespace Latan
 {
     template <>
-    IoObject::IoType MatSample<double>::getType(void) const
+    IoObject::IoType StatArray<Mat<double>, -1>::getType(void) const
     {
         return IoType::dMatSample;
     }
diff --git a/lib/StatArray.hpp b/lib/StatArray.hpp
index 3f92485..67903d2 100644
--- a/lib/StatArray.hpp
+++ b/lib/StatArray.hpp
@@ -33,7 +33,7 @@ BEGIN_LATAN_NAMESPACE
  *                     Array class with statistics                            *
  ******************************************************************************/
 template <typename T, Index os = 0>
-class StatArray: public Array<T, dynamic, 1>
+class StatArray: public Array<T, dynamic, 1>, public IoObject
 {
 protected:
     typedef Array<T, dynamic, 1> Base;
@@ -60,8 +60,10 @@ public:
     T    variance(const Index pos = 0, const Index n = -1) const;
     T    varianceMatrix(const Index pos = 0, const Index n = -1) const;
     T    correlationMatrix(const Index pos = 0, const Index n = -1) const;
+    // IO type
+    virtual IoType getType(void) const;
 public:
-    static const Index offset = os;
+    static constexpr Index offset = os;
 };
 
 // reduction operations
@@ -77,12 +79,10 @@ namespace ReducOp
 }
 
 // Sample types
-#define SAMPLE_OFFSET 1
-
-const int central = -SAMPLE_OFFSET;
+const int central = -1;
 
 template <typename T>
-using Sample = StatArray<T, SAMPLE_OFFSET>;
+using Sample = StatArray<T, 1>;
 
 typedef Sample<double>               DSample;
 typedef Sample<std::complex<double>> CSample;
@@ -273,6 +273,13 @@ namespace ReducOp
     }
 }
 
+// IO type /////////////////////////////////////////////////////////////////////
+template <typename T, Index os>
+IoObject::IoType StatArray<T, os>::getType(void) const
+{
+    return IoType::noType;
+}
+
 END_LATAN_NAMESPACE
 
 #endif // Latan_StatArray_hpp_
diff --git a/utils/make_fake_sample.cpp b/utils/make_fake_sample.cpp
index 8b8b5dd..c0e9757 100644
--- a/utils/make_fake_sample.cpp
+++ b/utils/make_fake_sample.cpp
@@ -42,21 +42,21 @@ int main(int argc, char *argv[])
     nSample     = strTo<Index>(argv[3]);
     outFileName = argv[4];
 
-    RandGen    gen;
-    DMatSample res(nSample, 1, 1);
+    RandGen gen;
+    DSample res(nSample);
 
     FOR_STAT_ARRAY(res, s)
     {
         if (s == central)
         {
-            res[s](0, 0) = val;
+            res[s] = val;
         }
         else
         {
-            res[s](0, 0) = gen.gaussian(val, err);
+            res[s] = gen.gaussian(val, err);
         }
     }
-    Io::save<DMatSample>(res, outFileName);
+    Io::save<DSample>(res, outFileName);
 
     return EXIT_SUCCESS;
 }
diff --git a/utils/sample_combine.cpp b/utils/sample_combine.cpp
index b313af7..35481d2 100644
--- a/utils/sample_combine.cpp
+++ b/utils/sample_combine.cpp
@@ -35,6 +35,108 @@ static void usage(const string &cmdName)
     exit(EXIT_FAILURE);
 }
 
+template <typename T>
+static void loadAndCheck(vector<T> &sample, const vector<string> &fileName)
+{
+    const unsigned int n = sample.size();
+    Index              nSample = 0;
+    
+    cout << "-- loading data..." << endl;
+    for (unsigned int i = 0; i < n; ++i)
+    {
+        sample[i] = Io::load<T>(fileName[i]);
+        if (i == 0)
+        {
+            nSample = sample[i].size();
+        }
+        else if (sample[i].size() != nSample)
+        {
+            cerr << "error: number of sample mismatch (between '";
+            cerr << fileName[0] << "' and '" << fileName[i] << "')" << endl;
+            abort();
+        }
+    }
+}
+
+template <typename T>
+static void combine(const string &outFileName __dumb,
+                    const vector<T> &sample __dumb, const string &code __dumb)
+{
+    abort();
+}
+
+template <>
+void combine(const string &outFileName, const vector<DSample> &sample,
+             const string &code)
+{
+    const unsigned int n = sample.size();
+    DoubleFunction     f = compile(code, n);
+    DSample            result(sample[0]);
+    DVec               buf(n);
+    
+    cout << "-- combining data..." << endl;
+    result = sample[0];
+    FOR_STAT_ARRAY(result, s)
+    {
+        for (unsigned int k = 0; k < n; ++k)
+        {
+            buf[k] = sample[k][s];
+        }
+        result[s] = f(buf);
+    }
+    cout << scientific;
+    cout << "central value:\n"      << result[central];
+    cout << endl;
+    cout << "standard deviation:\n" << sqrt(result.variance());
+    cout << endl;
+    if (!outFileName.empty())
+    {
+        Io::save<DSample>(result, outFileName);
+    }
+}
+
+template <>
+void combine(const string &outFileName, const vector<DMatSample> &sample,
+             const string &code)
+{
+    const unsigned int n = sample.size();
+    DoubleFunction     f = compile(code, n);
+    DVec               buf(n);
+    DMatSample         result(sample[0]);
+    
+    cout << "-- combining data..." << endl;
+    FOR_STAT_ARRAY(result, s)
+    {
+        FOR_MAT(result[s], i, j)
+        {
+            for (unsigned int k = 0; k < n; ++k)
+            {
+                buf[k] = sample[k][s](i,j);
+            }
+            result[s](i, j) = f(buf);
+        }
+    }
+    cout << scientific;
+    cout << "central value:\n"      << result[central];
+    cout << endl;
+    cout << "standard deviation:\n" << result.variance().cwiseSqrt();
+    cout << endl;
+    if (!outFileName.empty())
+    {
+        Io::save<DMatSample>(result, outFileName);
+    }
+}
+
+template <typename T>
+void process(const string &outFileName, const vector<string> &fileName,
+             const string &code)
+{
+    vector<T> sample(fileName.size());
+    
+    loadAndCheck(sample, fileName);
+    combine(outFileName, sample, code);
+}
+
 int main(int argc, char *argv[])
 {
     // argument parsing ////////////////////////////////////////////////////////
@@ -82,54 +184,16 @@ int main(int argc, char *argv[])
     {
         usage(cmdName);
     }
-
-    // data loading ////////////////////////////////////////////////////////////
-    vector<DMatSample> sample(n);
-    Index              nSample = 0;
-
-    cout << "-- loading data..." << endl;
-    for (unsigned int i = 0; i < n; ++i)
+    
+    // process data ////////////////////////////////////////////////////////////
+    try
     {
-        sample[i] = Io::load<DMatSample>(fileName[i]);
-        if (i == 0)
-        {
-            nSample = sample[i].size();
-        }
-        else if (sample[i].size() != nSample)
-        {
-            cerr << "error: number of sample mismatch (between '";
-            cerr << fileName[0] << "' and '" << fileName[i] << "')" << endl;
-
-            return EXIT_FAILURE;
-        }
+        process<DSample>(outFileName, fileName, code);
     }
-
-    // combine data ////////////////////////////////////////////////////////////
-    DoubleFunction f = compile(code, n);
-    DVec           buf(n);
-    DMatSample     result(sample[0]);
-
-    cout << "-- combining data..." << endl;
-    FOR_STAT_ARRAY(result, s)
+    catch (bad_cast &e)
     {
-        FOR_MAT(result[s], i, j)
-        {
-            for (unsigned int k = 0; k < n; ++k)
-            {
-                buf[k] = sample[k][s](i,j);
-            }
-            result[s](i, j) = f(buf);
-        }
+        process<DMatSample>(outFileName, fileName, code);
     }
-
-    // output //////////////////////////////////////////////////////////////////
-    cout << scientific;
-    cout << "central value:\n"      << result[central]               << endl;
-    cout << "standard deviation:\n" << result.variance().cwiseSqrt() << endl;
-    if (!outFileName.empty())
-    {
-        Io::save<DMatSample>(result, outFileName);
-    }
-
+    
     return EXIT_SUCCESS;
 }
diff --git a/utils/sample_read.cpp b/utils/sample_read.cpp
index 59bf2f3..1ce1f4b 100644
--- a/utils/sample_read.cpp
+++ b/utils/sample_read.cpp
@@ -35,14 +35,29 @@ int main(int argc, char *argv[])
     string fileName = argv[1], copy = (argc >= 3) ? argv[2] : "";
     
     cout << "-- loading sample from '" << fileName << "'..." << endl;
-    DMatSample s    = Io::load<DMatSample>(fileName);
-    string     name = Io::getFirstName(fileName);
-    cout << scientific;
-    cout << "central value:\n"      << s[central]               << endl;
-    cout << "standard deviation:\n" << s.variance().cwiseSqrt() << endl;
-    if (!copy.empty())
+    try
     {
-        Io::save(s, copy, File::Mode::write, name);
+        DMatSample s    = Io::load<DMatSample>(fileName);
+        string     name = Io::getFirstName(fileName);
+        cout << scientific;
+        cout << "central value:\n"      << s[central]               << endl;
+        cout << "standard deviation:\n" << s.variance().cwiseSqrt() << endl;
+        if (!copy.empty())
+        {
+            Io::save(s, copy, File::Mode::write, name);
+        }
+    }
+    catch (bad_cast &e)
+    {
+        DSample s    = Io::load<DSample>(fileName);
+        string  name = Io::getFirstName(fileName);
+        cout << scientific;
+        cout << "central value:\n"      << s[central]         << endl;
+        cout << "standard deviation:\n" << sqrt(s.variance()) << endl;
+        if (!copy.empty())
+        {
+            Io::save(s, copy, File::Mode::write, name);
+        }
     }
     
     return EXIT_SUCCESS;