diff --git a/array_core/array_core.h b/array_core/array_core.h
index d10b7c2..71727e7 100644
--- a/array_core/array_core.h
+++ b/array_core/array_core.h
@@ -10,60 +10,58 @@
 #include "configurator.h"
 #include "multi_plot.h"
 
+
 namespace dv {
 //#START_GRAB_TO_DV_NAMESPACE
 
-using std::vector;
-using std::string;
-
 
 //! (matrix) 2-dimensional array
 template <typename T>
 bool show(T** data, uint64_t arrRows, uint64_t arrCols,
-          const string& htmlPageName = dvs::makeUniqueDavisHtmlName(), const Config& configuration = Config());
+          const std::string& htmlPageName = dvs::makeUniqueDavisHtmlName(), const Config& configuration = Config());
 
 template <typename T>
-bool save(T** data, uint64_t arrRows, uint64_t arrCols, const string& filename,
+bool save(T** data, uint64_t arrRows, uint64_t arrCols, const std::string& filename,
           const configSaveToDisk& configuration = configSaveToDisk());
 
 //! (matrix) 1-dimensional array that simulates a 2-dimensional one (element access [i*cols+j])
 template <typename T>
 bool show(const T* data, uint64_t arrRows, uint64_t arrCols,
-          const string& htmlPageName = dvs::makeUniqueDavisHtmlName(), const Config& configuration = Config());
+          const std::string& htmlPageName = dvs::makeUniqueDavisHtmlName(), const Config& configuration = Config());
 
 template <typename T>
-bool save(const T* data, uint64_t arrRows, uint64_t arrCols, const string& filename,
+bool save(const T* data, uint64_t arrRows, uint64_t arrCols, const std::string& filename,
           const configSaveToDisk& configuration = configSaveToDisk());
 
 //! (chart) 1-dimensional array
 template <typename T>
-bool show(const T* data, uint64_t count, const string& htmlPageName = dvs::makeUniqueDavisHtmlName(), const Config& configuration = Config());
+bool show(const T* data, uint64_t count, const std::string& htmlPageName = dvs::makeUniqueDavisHtmlName(), const Config& configuration = Config());
 
 template <typename T>
-bool save(const T* data, uint64_t count, const string& filename, const configSaveToDisk& configuration = configSaveToDisk());
+bool save(const T* data, uint64_t count, const std::string& filename, const configSaveToDisk& configuration = configSaveToDisk());
 
 //! +(chart) 1-dimensional container
 template<typename C,
          typename T = typename std::decay<decltype(*std::begin(std::declval<C>()))>::type,
          typename Enable = typename std::enable_if<std::is_convertible<T, double>::value>::type>
-bool show(C const& container, const string& htmlPageName = dvs::makeUniqueDavisHtmlName(), const Config& configuration = Config());
+bool show(C const& container, const std::string& htmlPageName = dvs::makeUniqueDavisHtmlName(), const Config& configuration = Config());
 
 template<typename C,
          typename T = typename std::decay<decltype(*std::begin(std::declval<C>()))>::type,
          typename Enable = typename std::enable_if<std::is_convertible<T, double>::value>::type>
-bool save(C const& container, const string& filename, const configSaveToDisk& configuration = configSaveToDisk());
+bool save(C const& container, const std::string& filename, const configSaveToDisk& configuration = configSaveToDisk());
 
 
 //! +(chart) Two 1-dimensional container for X-Y plot
 template<typename C,
          typename T = typename std::decay<decltype(*std::begin(std::declval<C>()))>::type,
          typename Enable = typename std::enable_if<std::is_convertible<T, double>::value>::type>
-bool show(C const& containerX, C const& containerY, const string& htmlPageName = dvs::makeUniqueDavisHtmlName(), const Config& configuration = Config());
+bool show(C const& containerX, C const& containerY, const std::string& htmlPageName = dvs::makeUniqueDavisHtmlName(), const Config& configuration = Config());
 
 template<typename C,
          typename T = typename std::decay<decltype(*std::begin(std::declval<C>()))>::type,
          typename Enable = typename std::enable_if<std::is_convertible<T, double>::value>::type>
-bool save(C const& containerX, C const& containerY, const string& filename, const configSaveToDisk& configuration = configSaveToDisk());
+bool save(C const& containerX, C const& containerY, const std::string& filename, const configSaveToDisk& configuration = configSaveToDisk());
 
 
 //! (chart / matrix) 2-dimensional container
@@ -71,13 +69,13 @@ template<typename C,
          typename E = typename std::decay<decltype(*std::begin(std::declval<C>()))>::type,
          typename T = typename std::decay<decltype(*std::begin(std::declval<E>()))>::type,
          typename Enable = typename std::enable_if<std::is_convertible<T, double>::value>::type>
-bool show(C const& container_of_containers, const string& htmlPageName = dvs::makeUniqueDavisHtmlName(), const Config& configuration = Config());
+bool show(C const& container_of_containers, const std::string& htmlPageName = dvs::makeUniqueDavisHtmlName(), const Config& configuration = Config());
 
 template<typename C,
          typename E = typename std::decay<decltype(*std::begin(std::declval<C>()))>::type,
          typename T = typename std::decay<decltype(*std::begin(std::declval<E>()))>::type,
          typename Enable = typename std::enable_if<std::is_convertible<T, double>::value>::type>
-bool save(C const& container_of_containers, const string& filename, const configSaveToDisk& configuration = configSaveToDisk());
+bool save(C const& container_of_containers, const std::string& filename, const configSaveToDisk& configuration = configSaveToDisk());
 
 
 // ***********************************
@@ -85,13 +83,13 @@ bool save(C const& container_of_containers, const string& filename, const config
 // ***********************************
 
 template <typename T>
-bool show(T** data, uint64_t arrRows, uint64_t arrCols, const string& htmlPageName, const Config& configuration) {
-  vector<vector<double>> vecVecDbl;
-  vecVecDbl.reserve(arrRows);
-  for (uint64_t i = 0; i < arrRows; ++i) {
-    vector<double> dblRow(&data[i][0], &data[i][0] + arrCols);
-    vecVecDbl.emplace_back(dblRow);
-  }
+bool show(T** data, uint64_t arrRows, uint64_t arrCols, const std::string& htmlPageName, const Config& configuration) {
+  if (data == nullptr || arrRows == 0 || arrCols == 0)
+    return false;
+
+  std::vector<std::vector<double>> vecVecDbl =
+                                    dvs::makeVecVecFromRowPtr<double>(data, arrRows, arrCols);
+
   bool res = false;
   if (configuration.typeVisual == VISUALTYPE_AUTO ||
       configuration.typeVisual == VISUALTYPE_HEATMAP) {
@@ -102,24 +100,19 @@ bool show(T** data, uint64_t arrRows, uint64_t arrCols, const string& htmlPageNa
 
 template <typename T>
 bool save(T** data, uint64_t arrRows, uint64_t arrCols, const std::string& filename, const configSaveToDisk& configuration) {
-  vector<vector<T>> vecVec;
-  vecVec.reserve(arrRows);
-  for (uint64_t i = 0; i < arrRows; ++i) {
-    vector<T> row(&data[i][0], &data[i][0] + arrCols);
-    vecVec.emplace_back(row);
-  }
+  if (data == nullptr || arrRows == 0 || arrCols == 0)
+    return false;
+  std::vector<std::vector<T>> vecVec =
+                               dvs::makeVecVecFromRowPtr<T>(data, arrRows, arrCols);
   bool res = dvs::saveVecVec<T>(vecVec, filename, configuration);
   return res;
 }
 
 template <typename T>
-bool show(const T* data, uint64_t arrRows, uint64_t arrCols, const string& htmlPageName, const Config& configuration) {
-  vector<vector<double>> vecVecDbl;
-  vecVecDbl.reserve(arrRows);
-  for (uint64_t i = 0; i < arrRows; ++i) {
-    vector<double> dblRow(&data[i * arrCols], &data[i * arrCols] + arrCols);
-    vecVecDbl.emplace_back(dblRow);
-  }
+bool show(const T* data, uint64_t arrRows, uint64_t arrCols, const std::string& htmlPageName, const Config& configuration) {
+  if (data == nullptr || arrRows == 0 || arrCols == 0)
+    return false;
+  std::vector<std::vector<double>> vecVecDbl = dvs::makeVecVecFromFlat<double>(data, arrRows, arrCols);
   bool res = false;
   if (configuration.typeVisual == VISUALTYPE_AUTO ||
       configuration.typeVisual == VISUALTYPE_HEATMAP) {
@@ -129,21 +122,20 @@ bool show(const T* data, uint64_t arrRows, uint64_t arrCols, const string& htmlP
 }
 
 template <typename T>
-bool save(const T* data, uint64_t arrRows, uint64_t arrCols, const string& filename,
+bool save(const T* data, uint64_t arrRows, uint64_t arrCols, const std::string& filename,
           const configSaveToDisk& configuration) {
-  vector<vector<T>> vecVec;
-  vecVec.reserve(arrRows);
-  for (uint64_t i = 0; i < arrRows; ++i) {
-    vector<T> row(&data[i * arrCols], &data[i * arrCols] + arrCols);
-    vecVec.emplace_back(row);
-  }
+  if (data == nullptr || arrRows == 0 || arrCols == 0)
+    return false;
+  std::vector<std::vector<T>> vecVec = dvs::makeVecVecFromFlat<T>(data, arrRows, arrCols);
   bool res = dvs::saveVecVec<T>(vecVec, filename, configuration);
   return res;
 }
 
 template <typename T>
-bool show(const T* data, uint64_t count, const string& htmlPageName, const Config& configuration) {
-  vector<double> dblRow(data, data + count);
+bool show(const T* data, uint64_t count, const std::string& htmlPageName, const Config& configuration) {
+  if (data == nullptr || count == 0)
+    return false;
+  std::vector<double> dblRow = dvs::makeVecFrom1D<double>(data, count);
   bool res = false;
   if (configuration.typeVisual == VISUALTYPE_AUTO ||
       configuration.typeVisual == VISUALTYPE_CHART) {
@@ -158,15 +150,17 @@ bool show(const T* data, uint64_t count, const string& htmlPageName, const Confi
 }
 
 template <typename T>
-bool save(const T* data, uint64_t count, const string& filename, const configSaveToDisk& configuration) {
-  vector<T> row(data, data + count);
+bool save(const T* data, uint64_t count, const std::string& filename, const configSaveToDisk& configuration) {
+  if (data == nullptr || count == 0)
+    return false;
+  std::vector<T> row = dvs::makeVecFrom1D<T>(data, count);
   bool res = dvs::saveVec<T>(row, filename, configuration);
   return res;
 }
 
 template<typename C, typename T, typename>
-bool show(C const& container, const string& htmlPageName, const Config& configuration) {
-  vector<double> dblRow = dvs::vecFromTemplate<double>(container);
+bool show(C const& container, const std::string& htmlPageName, const Config& configuration) {
+  std::vector<double> dblRow = dvs::makeVecFromContainer<double>(container);
   bool res = false;
   if (configuration.typeVisual == VISUALTYPE_AUTO ||
       configuration.typeVisual == VISUALTYPE_CHART) {
@@ -181,19 +175,19 @@ bool show(C const& container, const string& htmlPageName, const Config& configur
 }
 
 template<typename C, typename T, typename>
-bool save(C const& container, const string& filename, const configSaveToDisk& configuration) {
-  vector<T> row = dvs::vecFromTemplate<T>(container);
+bool save(C const& container, const std::string& filename, const configSaveToDisk& configuration) {
+  std::vector<T> row = dvs::makeVecFromContainer<T>(container);
   bool res = dvs::saveVec<T>(row, filename, configuration);
   return res;
 }
 
 template<typename C, typename T, typename>
-bool show(C const& containerX, C const& containerY, const string& htmlPageName, const Config& configuration) {
+bool show(C const& containerX, C const& containerY, const std::string& htmlPageName, const Config& configuration) {
   if (containerX.size() != containerY.size()) {
     return false;
   }
-  vector<double> dblRowX = dvs::vecFromTemplate<double>(containerX);
-  vector<double> dblRowY = dvs::vecFromTemplate<double>(containerY);
+  std::vector<double> dblRowX = dvs::makeVecFromContainer<double>(containerX);
+  std::vector<double> dblRowY = dvs::makeVecFromContainer<double>(containerY);
 
   bool res = false;
   if (!dvs::isHold) {
@@ -206,13 +200,13 @@ bool show(C const& containerX, C const& containerY, const string& htmlPageName,
 }
 
 template<typename C, typename T, typename Enable>
-bool save(C const& containerX, C const& containerY,  const string& filename, const configSaveToDisk& configuration) {
+bool save(C const& containerX, C const& containerY,  const std::string& filename, const configSaveToDisk& configuration) {
   if (containerX.size() != containerY.size()) {
     return false;
   }
-  vector<T> rowX = dvs::vecFromTemplate<T>(containerX);
-  vector<T> rowY = dvs::vecFromTemplate<T>(containerY);
-  vector<vector<T>> vecVec;
+  std::vector<T> rowX = dvs::makeVecFromContainer<T>(containerX);
+  std::vector<T> rowY = dvs::makeVecFromContainer<T>(containerY);
+  std::vector<std::vector<T>> vecVec;
   vecVec.emplace_back(rowX);
   vecVec.emplace_back(rowY);
   configSaveToDisk newConf = configuration;
@@ -222,11 +216,11 @@ bool save(C const& containerX, C const& containerY,  const string& filename, con
 }
 
 template<typename C, typename E, typename T, typename >
-bool show(C const& container_of_containers, const string& htmlPageName, const Config& configuration) {
-  vector<vector<double>> vecVecDbl;
+bool show(C const& container_of_containers, const std::string& htmlPageName, const Config& configuration) {
+  std::vector<std::vector<double>> vecVecDbl;
   vecVecDbl.reserve(container_of_containers.size());
-  for (auto row : container_of_containers) {
-    vector<double> dblRow = dvs::vecFromTemplate<double>(row);
+  for (const auto& row : container_of_containers) {
+    std::vector<double> dblRow = dvs::makeVecFromContainer<double>(row);
     vecVecDbl.emplace_back(dblRow);
   }
   bool res = false;
@@ -238,14 +232,14 @@ bool show(C const& container_of_containers, const string& htmlPageName, const Co
   if ((configuration.typeVisual == VISUALTYPE_AUTO || //case when we want to plot graph with X and Y vectors
        configuration.typeVisual == VISUALTYPE_CHART) &&
       (size1 == 2 || size2 == 2)) { // it can be or 2-columns-data or 2-rows-data
-    vector<double> xVals;
-    vector<double> yVals;
+    std::vector<double> xVals;
+    std::vector<double> yVals;
     if (size1 == 2) {
       xVals = vecVecDbl[0];
       yVals = vecVecDbl[1];
     } else if (size2 == 2) {
       xVals.reserve(size1);
-      for (int i = 0; i < size1; ++i) {
+      for (size_t i = 0; i < size1; ++i) {
         xVals.emplace_back(vecVecDbl[i][0]);
         yVals.emplace_back(vecVecDbl[i][1]);
       }
@@ -264,11 +258,11 @@ bool show(C const& container_of_containers, const string& htmlPageName, const Co
 }
 
 template<typename C, typename E, typename T, typename Enable>
-bool save(C const& container_of_containers, const string& filename, const configSaveToDisk& configuration) {
-  vector<vector<T>> vecVec;
+bool save(C const& container_of_containers, const std::string& filename, const configSaveToDisk& configuration) {
+  std::vector<std::vector<T>> vecVec;
   vecVec.reserve(container_of_containers.size());
-  for (auto row : container_of_containers) {
-    vector<T> rowTemp = dvs::vecFromTemplate<T>(row);
+  for (const auto& row : container_of_containers) {
+    std::vector<T> rowTemp = dvs::makeVecFromContainer<T>(row);
     vecVec.emplace_back(rowTemp);
   }
   bool res = dvs::saveVecVec<T>(vecVec, filename, configuration);
diff --git a/array_core/multi_plot.cpp b/array_core/multi_plot.cpp
index 4919db8..26e9ce0 100644
--- a/array_core/multi_plot.cpp
+++ b/array_core/multi_plot.cpp
@@ -1,5 +1,6 @@
 #include "multi_plot.h"
 #include "plotly_maker/html_parts.h"
+#include "plotly_maker/plotly_maker.h"
 #include "common_utils/common_utils.h"
 #include "common_utils/common_constants.h"
 
@@ -7,7 +8,7 @@ namespace dvs {
 //#START_GRAB_TO_DVS_NAMESPACE
 
 bool isHold = false;
-vector<string> allChartBlocks = {};
+std::vector<std::string> allChartBlocks = {};
 
 //#STOP_GRAB_TO_DVS_NAMESPACE
 } // end namespace dvs
@@ -27,25 +28,25 @@ void holdOff(const Config& configuration) {
   if (dvs::allChartBlocks.empty()) {
     return;
   }
-  string allTracesNames_str;
-  string allChartBlocks_str;
-  const string trace_name_part = "trace";
+  std::string allTracesNames_str;
+  std::string allChartBlocks_str;
+  const std::string trace_name_part = "trace";
   for (int i = 0; i < dvs::allChartBlocks.size(); ++i) {
-    string str_numTrace = std::to_string(i + 1);
-    string filled_trace_name_part = trace_name_part + str_numTrace;
+    std::string str_numTrace = std::to_string(i + 1);
+    std::string filled_trace_name_part = trace_name_part + str_numTrace;
     if (i < dvs::allChartBlocks.size() - 1) {
       filled_trace_name_part.append(",");
     }
     allTracesNames_str.append(filled_trace_name_part);
     allChartBlocks_str.append(dvs::allChartBlocks[i]);
   }
-  string paramWH;
+  std::string paramWH;
   if (configuration.chart.aspectRatioWidth > configuration.chart.aspectRatioHeight) {
     paramWH = "width";
   } else {
     paramWH = "height";
   }
-  string paramWHsecond;
+  std::string paramWHsecond;
   if (configuration.chart.isFitPlotToWindow) {
     if (paramWH == "width") {
       paramWHsecond = "height";
@@ -55,27 +56,32 @@ void holdOff(const Config& configuration) {
   } else {
     paramWHsecond = paramWH;
   }
-  vector<string> args = {dvs::kPlotlyJsName,
-                         allChartBlocks_str,
-                         allTracesNames_str,
-                         configuration.chart.title,
-                         configuration.chart.xLabel,
-                         configuration.chart.yLabel,
-                         dvs::toStringDotSeparator(configuration.chart.aspectRatioWidth),
-                         dvs::toStringDotSeparator(configuration.chart.aspectRatioHeight),
-                         paramWH,
-                         paramWHsecond,
-                         dvs::kHtmlComboboxStyleBlock,
-                         dvs::kHtmlComboboxSelectBlock,
-                         dvs::kHtmlComboboxUpdateFooBlock,
-                         dvs::kHtmlDavisLogoHyperlinkBlock
-                        };
-  string multichartPage = dvs::kHtmlMultiChartModel;
-  string filled_multichartPage = "";
+  std::vector<std::string> args = {dvs::kPlotlyJsName,
+                                   allChartBlocks_str,
+                                   allTracesNames_str,
+                                   configuration.chart.title,
+                                   configuration.chart.xLabel,
+                                   configuration.chart.yLabel,
+                                   dvs::toStringDotSeparator(configuration.chart.aspectRatioWidth),
+                                   dvs::toStringDotSeparator(configuration.chart.aspectRatioHeight),
+                                   paramWH,
+                                   paramWHsecond,
+                                   dvs::kHtmlComboboxStyleBlock,
+                                   dvs::kHtmlComboboxSelectBlock,
+                                   dvs::kHtmlComboboxUpdateFooBlock,
+                                   dvs::kHtmlDavisLogoHyperlinkBlock
+                                  };
+  std::string multichartPage = dvs::kHtmlMultiChartModel;
+  std::string filled_multichartPage = "";
   dvs::make_string(multichartPage, args, filled_multichartPage);
-  string htmlFullName = dvs::makeUniqueDavisHtmlRelativePath();
+  std::string htmlFullName = dvs::makeUniqueDavisHtmlRelativePath();
+  dvs::mayBeCreateJsWorkingFolder();
   dvs::saveStringToFile(htmlFullName, filled_multichartPage);
-  dvs::openFileBySystem(htmlFullName);
+  if (dvs::isPlotlyScriptExists()) {
+    dvs::openPlotlyHtml(htmlFullName);
+  } else {
+    dvs::showWarningJsAbsentPage();
+  }
   dvs::allChartBlocks.clear();
 }
 
diff --git a/common_utils/common_utils.h b/common_utils/common_utils.h
index 473e00e..461aa1a 100644
--- a/common_utils/common_utils.h
+++ b/common_utils/common_utils.h
@@ -147,12 +147,12 @@ bool saveVecVec(const vector<vector<T>>& vecVec, const string& filename, dv::con
   return true;
 }
 
-//! convert any container to std::vector with G type
+//! convert any container to std::vector<G>
 template<typename G,
          typename C, //https://devblogs.microsoft.com/oldnewthing/20190619-00/?p=102599
          typename T = typename std::decay<decltype(*std::begin(std::declval<C>()))>::type,
          typename Enable = typename std::enable_if<std::is_convertible<T, G>::value>::type>
-std::vector<G> vecFromTemplate(const C& container) {
+std::vector<G> makeVecFromContainer(const C& container) {
   std::vector<G> vec;
   vec.reserve(static_cast<size_t>(std::distance(std::begin(container), std::end(container))));
   for (auto const& v : container) {
@@ -161,9 +161,49 @@ std::vector<G> vecFromTemplate(const C& container) {
   return vec;
 }
 
+//! convert T** to std::vector<G>
+template <typename G, typename T>
+inline std::vector<std::vector<G>> makeVecVecFromRowPtr(const T* const* data, uint64_t rows, uint64_t cols) {
+  std::vector<std::vector<G>> res;
+  res.reserve(rows);
+  for (uint64_t i = 0; i < rows; ++i) {
+    const T* rowPtr = data[i];
+    std::vector<G> row;
+    row.reserve(cols);
+    for (uint64_t j = 0; j < cols; ++j)
+      row.push_back(static_cast<G>(rowPtr[j]));
+    res.emplace_back(std::move(row));
+  }
+  return res;
+}
 
-bool is_string_convertable_to_digit(const string& sample);
+//! convert pseudo 2D T* to std::vector<G>
+template <typename G, typename T>
+inline std::vector<std::vector<G>> makeVecVecFromFlat(const T* data, uint64_t rows, uint64_t cols) {
+  std::vector<std::vector<G>> res;
+  res.reserve(rows);
+  for (uint64_t i = 0; i < rows; ++i) {
+    const T* rowPtr = data + i * cols;
+    std::vector<G> row;
+    row.reserve(cols);
+    for (uint64_t j = 0; j < cols; ++j)
+      row.push_back(static_cast<G>(rowPtr[j]));
+    res.emplace_back(std::move(row));
+  }
+  return res;
+}
+
+//! convert pseudo T* to std::vector<G>
+template <typename G, typename T>
+inline std::vector<G> makeVecFrom1D(const T* data, uint64_t count) {
+  std::vector<G> res;
+  res.reserve(static_cast<size_t>(count));
+  for (uint64_t i = 0; i < count; ++i)
+    res.push_back(static_cast<G>(data[i]));
+  return res;
+}
 
+bool is_string_convertable_to_digit(const string& sample);
 
 void transponeMatrix(std::vector<std::vector<double>>& matrix);
 
diff --git a/davis_one/davis.cpp b/davis_one/davis.cpp
index a3d6793..c84aa72 100644
--- a/davis_one/davis.cpp
+++ b/davis_one/davis.cpp
@@ -1780,7 +1780,7 @@ void showMultiChart(const std::string& date_time_values,
 namespace dvs {
 
 bool isHold = false;
-vector<string> allChartBlocks = {};
+std::vector<std::string> allChartBlocks = {};
 
 
 } // namespace dvs end
@@ -1798,25 +1798,25 @@ void holdOff(const Config& configuration) {
   if (dvs::allChartBlocks.empty()) {
     return;
   }
-  string allTracesNames_str;
-  string allChartBlocks_str;
-  const string trace_name_part = "trace";
+  std::string allTracesNames_str;
+  std::string allChartBlocks_str;
+  const std::string trace_name_part = "trace";
   for (int i = 0; i < dvs::allChartBlocks.size(); ++i) {
-    string str_numTrace = std::to_string(i + 1);
-    string filled_trace_name_part = trace_name_part + str_numTrace;
+    std::string str_numTrace = std::to_string(i + 1);
+    std::string filled_trace_name_part = trace_name_part + str_numTrace;
     if (i < dvs::allChartBlocks.size() - 1) {
       filled_trace_name_part.append(",");
     }
     allTracesNames_str.append(filled_trace_name_part);
     allChartBlocks_str.append(dvs::allChartBlocks[i]);
   }
-  string paramWH;
+  std::string paramWH;
   if (configuration.chart.aspectRatioWidth > configuration.chart.aspectRatioHeight) {
     paramWH = "width";
   } else {
     paramWH = "height";
   }
-  string paramWHsecond;
+  std::string paramWHsecond;
   if (configuration.chart.isFitPlotToWindow) {
     if (paramWH == "width") {
       paramWHsecond = "height";
@@ -1826,27 +1826,32 @@ void holdOff(const Config& configuration) {
   } else {
     paramWHsecond = paramWH;
   }
-  vector<string> args = {dvs::kPlotlyJsName,
-                         allChartBlocks_str,
-                         allTracesNames_str,
-                         configuration.chart.title,
-                         configuration.chart.xLabel,
-                         configuration.chart.yLabel,
-                         dvs::toStringDotSeparator(configuration.chart.aspectRatioWidth),
-                         dvs::toStringDotSeparator(configuration.chart.aspectRatioHeight),
-                         paramWH,
-                         paramWHsecond,
-                         dvs::kHtmlComboboxStyleBlock,
-                         dvs::kHtmlComboboxSelectBlock,
-                         dvs::kHtmlComboboxUpdateFooBlock,
-                         dvs::kHtmlDavisLogoHyperlinkBlock
-                        };
-  string multichartPage = dvs::kHtmlMultiChartModel;
-  string filled_multichartPage = "";
+  std::vector<std::string> args = {dvs::kPlotlyJsName,
+                                   allChartBlocks_str,
+                                   allTracesNames_str,
+                                   configuration.chart.title,
+                                   configuration.chart.xLabel,
+                                   configuration.chart.yLabel,
+                                   dvs::toStringDotSeparator(configuration.chart.aspectRatioWidth),
+                                   dvs::toStringDotSeparator(configuration.chart.aspectRatioHeight),
+                                   paramWH,
+                                   paramWHsecond,
+                                   dvs::kHtmlComboboxStyleBlock,
+                                   dvs::kHtmlComboboxSelectBlock,
+                                   dvs::kHtmlComboboxUpdateFooBlock,
+                                   dvs::kHtmlDavisLogoHyperlinkBlock
+                                  };
+  std::string multichartPage = dvs::kHtmlMultiChartModel;
+  std::string filled_multichartPage = "";
   dvs::make_string(multichartPage, args, filled_multichartPage);
-  string htmlFullName = dvs::makeUniqueDavisHtmlRelativePath();
+  std::string htmlFullName = dvs::makeUniqueDavisHtmlRelativePath();
+  dvs::mayBeCreateJsWorkingFolder();
   dvs::saveStringToFile(htmlFullName, filled_multichartPage);
-  dvs::openFileBySystem(htmlFullName);
+  if (dvs::isPlotlyScriptExists()) {
+    dvs::openPlotlyHtml(htmlFullName);
+  } else {
+    dvs::showWarningJsAbsentPage();
+  }
   dvs::allChartBlocks.clear();
 }
 
diff --git a/davis_one/davis.h b/davis_one/davis.h
index c3990e9..37b7024 100644
--- a/davis_one/davis.h
+++ b/davis_one/davis.h
@@ -362,12 +362,12 @@ bool saveVecVec(const vector<vector<T>>& vecVec, const string& filename, dv::con
   return true;
 }
 
-//! convert any container to std::vector with G type
+//! convert any container to std::vector<G>
 template<typename G,
          typename C, //https://devblogs.microsoft.com/oldnewthing/20190619-00/?p=102599
          typename T = typename std::decay<decltype(*std::begin(std::declval<C>()))>::type,
          typename Enable = typename std::enable_if<std::is_convertible<T, G>::value>::type>
-std::vector<G> vecFromTemplate(const C& container) {
+std::vector<G> makeVecFromContainer(const C& container) {
   std::vector<G> vec;
   vec.reserve(static_cast<size_t>(std::distance(std::begin(container), std::end(container))));
   for (auto const& v : container) {
@@ -376,9 +376,49 @@ std::vector<G> vecFromTemplate(const C& container) {
   return vec;
 }
 
+//! convert T** to std::vector<G>
+template <typename G, typename T>
+inline std::vector<std::vector<G>> makeVecVecFromRowPtr(const T* const* data, uint64_t rows, uint64_t cols) {
+  std::vector<std::vector<G>> res;
+  res.reserve(rows);
+  for (uint64_t i = 0; i < rows; ++i) {
+    const T* rowPtr = data[i];
+    std::vector<G> row;
+    row.reserve(cols);
+    for (uint64_t j = 0; j < cols; ++j)
+      row.push_back(static_cast<G>(rowPtr[j]));
+    res.emplace_back(std::move(row));
+  }
+  return res;
+}
 
-bool is_string_convertable_to_digit(const string& sample);
+//! convert pseudo 2D T* to std::vector<G>
+template <typename G, typename T>
+inline std::vector<std::vector<G>> makeVecVecFromFlat(const T* data, uint64_t rows, uint64_t cols) {
+  std::vector<std::vector<G>> res;
+  res.reserve(rows);
+  for (uint64_t i = 0; i < rows; ++i) {
+    const T* rowPtr = data + i * cols;
+    std::vector<G> row;
+    row.reserve(cols);
+    for (uint64_t j = 0; j < cols; ++j)
+      row.push_back(static_cast<G>(rowPtr[j]));
+    res.emplace_back(std::move(row));
+  }
+  return res;
+}
 
+//! convert pseudo T* to std::vector<G>
+template <typename G, typename T>
+inline std::vector<G> makeVecFrom1D(const T* data, uint64_t count) {
+  std::vector<G> res;
+  res.reserve(static_cast<size_t>(count));
+  for (uint64_t i = 0; i < count; ++i)
+    res.push_back(static_cast<G>(data[i]));
+  return res;
+}
+
+bool is_string_convertable_to_digit(const string& sample);
 
 void transponeMatrix(std::vector<std::vector<double>>& matrix);
 
@@ -499,57 +539,54 @@ void holdOff(const Config& configuration = Config());
 } // namespace dv end
 namespace dv {
 
-using std::vector;
-using std::string;
-
 
 //! (matrix) 2-dimensional array
 template <typename T>
 bool show(T** data, uint64_t arrRows, uint64_t arrCols,
-          const string& htmlPageName = dvs::makeUniqueDavisHtmlName(), const Config& configuration = Config());
+          const std::string& htmlPageName = dvs::makeUniqueDavisHtmlName(), const Config& configuration = Config());
 
 template <typename T>
-bool save(T** data, uint64_t arrRows, uint64_t arrCols, const string& filename,
+bool save(T** data, uint64_t arrRows, uint64_t arrCols, const std::string& filename,
           const configSaveToDisk& configuration = configSaveToDisk());
 
 //! (matrix) 1-dimensional array that simulates a 2-dimensional one (element access [i*cols+j])
 template <typename T>
 bool show(const T* data, uint64_t arrRows, uint64_t arrCols,
-          const string& htmlPageName = dvs::makeUniqueDavisHtmlName(), const Config& configuration = Config());
+          const std::string& htmlPageName = dvs::makeUniqueDavisHtmlName(), const Config& configuration = Config());
 
 template <typename T>
-bool save(const T* data, uint64_t arrRows, uint64_t arrCols, const string& filename,
+bool save(const T* data, uint64_t arrRows, uint64_t arrCols, const std::string& filename,
           const configSaveToDisk& configuration = configSaveToDisk());
 
 //! (chart) 1-dimensional array
 template <typename T>
-bool show(const T* data, uint64_t count, const string& htmlPageName = dvs::makeUniqueDavisHtmlName(), const Config& configuration = Config());
+bool show(const T* data, uint64_t count, const std::string& htmlPageName = dvs::makeUniqueDavisHtmlName(), const Config& configuration = Config());
 
 template <typename T>
-bool save(const T* data, uint64_t count, const string& filename, const configSaveToDisk& configuration = configSaveToDisk());
+bool save(const T* data, uint64_t count, const std::string& filename, const configSaveToDisk& configuration = configSaveToDisk());
 
 //! +(chart) 1-dimensional container
 template<typename C,
          typename T = typename std::decay<decltype(*std::begin(std::declval<C>()))>::type,
          typename Enable = typename std::enable_if<std::is_convertible<T, double>::value>::type>
-bool show(C const& container, const string& htmlPageName = dvs::makeUniqueDavisHtmlName(), const Config& configuration = Config());
+bool show(C const& container, const std::string& htmlPageName = dvs::makeUniqueDavisHtmlName(), const Config& configuration = Config());
 
 template<typename C,
          typename T = typename std::decay<decltype(*std::begin(std::declval<C>()))>::type,
          typename Enable = typename std::enable_if<std::is_convertible<T, double>::value>::type>
-bool save(C const& container, const string& filename, const configSaveToDisk& configuration = configSaveToDisk());
+bool save(C const& container, const std::string& filename, const configSaveToDisk& configuration = configSaveToDisk());
 
 
 //! +(chart) Two 1-dimensional container for X-Y plot
 template<typename C,
          typename T = typename std::decay<decltype(*std::begin(std::declval<C>()))>::type,
          typename Enable = typename std::enable_if<std::is_convertible<T, double>::value>::type>
-bool show(C const& containerX, C const& containerY, const string& htmlPageName = dvs::makeUniqueDavisHtmlName(), const Config& configuration = Config());
+bool show(C const& containerX, C const& containerY, const std::string& htmlPageName = dvs::makeUniqueDavisHtmlName(), const Config& configuration = Config());
 
 template<typename C,
          typename T = typename std::decay<decltype(*std::begin(std::declval<C>()))>::type,
          typename Enable = typename std::enable_if<std::is_convertible<T, double>::value>::type>
-bool save(C const& containerX, C const& containerY, const string& filename, const configSaveToDisk& configuration = configSaveToDisk());
+bool save(C const& containerX, C const& containerY, const std::string& filename, const configSaveToDisk& configuration = configSaveToDisk());
 
 
 //! (chart / matrix) 2-dimensional container
@@ -557,13 +594,13 @@ template<typename C,
          typename E = typename std::decay<decltype(*std::begin(std::declval<C>()))>::type,
          typename T = typename std::decay<decltype(*std::begin(std::declval<E>()))>::type,
          typename Enable = typename std::enable_if<std::is_convertible<T, double>::value>::type>
-bool show(C const& container_of_containers, const string& htmlPageName = dvs::makeUniqueDavisHtmlName(), const Config& configuration = Config());
+bool show(C const& container_of_containers, const std::string& htmlPageName = dvs::makeUniqueDavisHtmlName(), const Config& configuration = Config());
 
 template<typename C,
          typename E = typename std::decay<decltype(*std::begin(std::declval<C>()))>::type,
          typename T = typename std::decay<decltype(*std::begin(std::declval<E>()))>::type,
          typename Enable = typename std::enable_if<std::is_convertible<T, double>::value>::type>
-bool save(C const& container_of_containers, const string& filename, const configSaveToDisk& configuration = configSaveToDisk());
+bool save(C const& container_of_containers, const std::string& filename, const configSaveToDisk& configuration = configSaveToDisk());
 
 
 // ***********************************
@@ -571,13 +608,13 @@ bool save(C const& container_of_containers, const string& filename, const config
 // ***********************************
 
 template <typename T>
-bool show(T** data, uint64_t arrRows, uint64_t arrCols, const string& htmlPageName, const Config& configuration) {
-  vector<vector<double>> vecVecDbl;
-  vecVecDbl.reserve(arrRows);
-  for (uint64_t i = 0; i < arrRows; ++i) {
-    vector<double> dblRow(&data[i][0], &data[i][0] + arrCols);
-    vecVecDbl.emplace_back(dblRow);
-  }
+bool show(T** data, uint64_t arrRows, uint64_t arrCols, const std::string& htmlPageName, const Config& configuration) {
+  if (data == nullptr || arrRows == 0 || arrCols == 0)
+    return false;
+
+  std::vector<std::vector<double>> vecVecDbl =
+                                    dvs::makeVecVecFromRowPtr<double>(data, arrRows, arrCols);
+
   bool res = false;
   if (configuration.typeVisual == VISUALTYPE_AUTO ||
       configuration.typeVisual == VISUALTYPE_HEATMAP) {
@@ -588,24 +625,19 @@ bool show(T** data, uint64_t arrRows, uint64_t arrCols, const string& htmlPageNa
 
 template <typename T>
 bool save(T** data, uint64_t arrRows, uint64_t arrCols, const std::string& filename, const configSaveToDisk& configuration) {
-  vector<vector<T>> vecVec;
-  vecVec.reserve(arrRows);
-  for (uint64_t i = 0; i < arrRows; ++i) {
-    vector<T> row(&data[i][0], &data[i][0] + arrCols);
-    vecVec.emplace_back(row);
-  }
+  if (data == nullptr || arrRows == 0 || arrCols == 0)
+    return false;
+  std::vector<std::vector<T>> vecVec =
+                               dvs::makeVecVecFromRowPtr<T>(data, arrRows, arrCols);
   bool res = dvs::saveVecVec<T>(vecVec, filename, configuration);
   return res;
 }
 
 template <typename T>
-bool show(const T* data, uint64_t arrRows, uint64_t arrCols, const string& htmlPageName, const Config& configuration) {
-  vector<vector<double>> vecVecDbl;
-  vecVecDbl.reserve(arrRows);
-  for (uint64_t i = 0; i < arrRows; ++i) {
-    vector<double> dblRow(&data[i * arrCols], &data[i * arrCols] + arrCols);
-    vecVecDbl.emplace_back(dblRow);
-  }
+bool show(const T* data, uint64_t arrRows, uint64_t arrCols, const std::string& htmlPageName, const Config& configuration) {
+  if (data == nullptr || arrRows == 0 || arrCols == 0)
+    return false;
+  std::vector<std::vector<double>> vecVecDbl = dvs::makeVecVecFromFlat<double>(data, arrRows, arrCols);
   bool res = false;
   if (configuration.typeVisual == VISUALTYPE_AUTO ||
       configuration.typeVisual == VISUALTYPE_HEATMAP) {
@@ -615,21 +647,20 @@ bool show(const T* data, uint64_t arrRows, uint64_t arrCols, const string& htmlP
 }
 
 template <typename T>
-bool save(const T* data, uint64_t arrRows, uint64_t arrCols, const string& filename,
+bool save(const T* data, uint64_t arrRows, uint64_t arrCols, const std::string& filename,
           const configSaveToDisk& configuration) {
-  vector<vector<T>> vecVec;
-  vecVec.reserve(arrRows);
-  for (uint64_t i = 0; i < arrRows; ++i) {
-    vector<T> row(&data[i * arrCols], &data[i * arrCols] + arrCols);
-    vecVec.emplace_back(row);
-  }
+  if (data == nullptr || arrRows == 0 || arrCols == 0)
+    return false;
+  std::vector<std::vector<T>> vecVec = dvs::makeVecVecFromFlat<T>(data, arrRows, arrCols);
   bool res = dvs::saveVecVec<T>(vecVec, filename, configuration);
   return res;
 }
 
 template <typename T>
-bool show(const T* data, uint64_t count, const string& htmlPageName, const Config& configuration) {
-  vector<double> dblRow(data, data + count);
+bool show(const T* data, uint64_t count, const std::string& htmlPageName, const Config& configuration) {
+  if (data == nullptr || count == 0)
+    return false;
+  std::vector<double> dblRow = dvs::makeVecFrom1D<double>(data, count);
   bool res = false;
   if (configuration.typeVisual == VISUALTYPE_AUTO ||
       configuration.typeVisual == VISUALTYPE_CHART) {
@@ -644,15 +675,17 @@ bool show(const T* data, uint64_t count, const string& htmlPageName, const Confi
 }
 
 template <typename T>
-bool save(const T* data, uint64_t count, const string& filename, const configSaveToDisk& configuration) {
-  vector<T> row(data, data + count);
+bool save(const T* data, uint64_t count, const std::string& filename, const configSaveToDisk& configuration) {
+  if (data == nullptr || count == 0)
+    return false;
+  std::vector<T> row = dvs::makeVecFrom1D<T>(data, count);
   bool res = dvs::saveVec<T>(row, filename, configuration);
   return res;
 }
 
 template<typename C, typename T, typename>
-bool show(C const& container, const string& htmlPageName, const Config& configuration) {
-  vector<double> dblRow = dvs::vecFromTemplate<double>(container);
+bool show(C const& container, const std::string& htmlPageName, const Config& configuration) {
+  std::vector<double> dblRow = dvs::makeVecFromContainer<double>(container);
   bool res = false;
   if (configuration.typeVisual == VISUALTYPE_AUTO ||
       configuration.typeVisual == VISUALTYPE_CHART) {
@@ -667,19 +700,19 @@ bool show(C const& container, const string& htmlPageName, const Config& configur
 }
 
 template<typename C, typename T, typename>
-bool save(C const& container, const string& filename, const configSaveToDisk& configuration) {
-  vector<T> row = dvs::vecFromTemplate<T>(container);
+bool save(C const& container, const std::string& filename, const configSaveToDisk& configuration) {
+  std::vector<T> row = dvs::makeVecFromContainer<T>(container);
   bool res = dvs::saveVec<T>(row, filename, configuration);
   return res;
 }
 
 template<typename C, typename T, typename>
-bool show(C const& containerX, C const& containerY, const string& htmlPageName, const Config& configuration) {
+bool show(C const& containerX, C const& containerY, const std::string& htmlPageName, const Config& configuration) {
   if (containerX.size() != containerY.size()) {
     return false;
   }
-  vector<double> dblRowX = dvs::vecFromTemplate<double>(containerX);
-  vector<double> dblRowY = dvs::vecFromTemplate<double>(containerY);
+  std::vector<double> dblRowX = dvs::makeVecFromContainer<double>(containerX);
+  std::vector<double> dblRowY = dvs::makeVecFromContainer<double>(containerY);
 
   bool res = false;
   if (!dvs::isHold) {
@@ -692,13 +725,13 @@ bool show(C const& containerX, C const& containerY, const string& htmlPageName,
 }
 
 template<typename C, typename T, typename Enable>
-bool save(C const& containerX, C const& containerY,  const string& filename, const configSaveToDisk& configuration) {
+bool save(C const& containerX, C const& containerY,  const std::string& filename, const configSaveToDisk& configuration) {
   if (containerX.size() != containerY.size()) {
     return false;
   }
-  vector<T> rowX = dvs::vecFromTemplate<T>(containerX);
-  vector<T> rowY = dvs::vecFromTemplate<T>(containerY);
-  vector<vector<T>> vecVec;
+  std::vector<T> rowX = dvs::makeVecFromContainer<T>(containerX);
+  std::vector<T> rowY = dvs::makeVecFromContainer<T>(containerY);
+  std::vector<std::vector<T>> vecVec;
   vecVec.emplace_back(rowX);
   vecVec.emplace_back(rowY);
   configSaveToDisk newConf = configuration;
@@ -708,11 +741,11 @@ bool save(C const& containerX, C const& containerY,  const string& filename, con
 }
 
 template<typename C, typename E, typename T, typename >
-bool show(C const& container_of_containers, const string& htmlPageName, const Config& configuration) {
-  vector<vector<double>> vecVecDbl;
+bool show(C const& container_of_containers, const std::string& htmlPageName, const Config& configuration) {
+  std::vector<std::vector<double>> vecVecDbl;
   vecVecDbl.reserve(container_of_containers.size());
-  for (auto row : container_of_containers) {
-    vector<double> dblRow = dvs::vecFromTemplate<double>(row);
+  for (const auto& row : container_of_containers) {
+    std::vector<double> dblRow = dvs::makeVecFromContainer<double>(row);
     vecVecDbl.emplace_back(dblRow);
   }
   bool res = false;
@@ -724,14 +757,14 @@ bool show(C const& container_of_containers, const string& htmlPageName, const Co
   if ((configuration.typeVisual == VISUALTYPE_AUTO || //case when we want to plot graph with X and Y vectors
        configuration.typeVisual == VISUALTYPE_CHART) &&
       (size1 == 2 || size2 == 2)) { // it can be or 2-columns-data or 2-rows-data
-    vector<double> xVals;
-    vector<double> yVals;
+    std::vector<double> xVals;
+    std::vector<double> yVals;
     if (size1 == 2) {
       xVals = vecVecDbl[0];
       yVals = vecVecDbl[1];
     } else if (size2 == 2) {
       xVals.reserve(size1);
-      for (int i = 0; i < size1; ++i) {
+      for (size_t i = 0; i < size1; ++i) {
         xVals.emplace_back(vecVecDbl[i][0]);
         yVals.emplace_back(vecVecDbl[i][1]);
       }
@@ -750,11 +783,11 @@ bool show(C const& container_of_containers, const string& htmlPageName, const Co
 }
 
 template<typename C, typename E, typename T, typename Enable>
-bool save(C const& container_of_containers, const string& filename, const configSaveToDisk& configuration) {
-  vector<vector<T>> vecVec;
+bool save(C const& container_of_containers, const std::string& filename, const configSaveToDisk& configuration) {
+  std::vector<std::vector<T>> vecVec;
   vecVec.reserve(container_of_containers.size());
-  for (auto row : container_of_containers) {
-    vector<T> rowTemp = dvs::vecFromTemplate<T>(row);
+  for (const auto& row : container_of_containers) {
+    std::vector<T> rowTemp = dvs::makeVecFromContainer<T>(row);
     vecVec.emplace_back(rowTemp);
   }
   bool res = dvs::saveVecVec<T>(vecVec, filename, configuration);