Compile errors fixed (2)

src/Waveform.cpp

@@ -92,9 +92,9 @@ std::ostringstream oss;
 
 //- FOR DEBUG : comment out Timer and STD::COUT !!
 yat::Timer t;
-std::size_t time_to_write_data;
-std::size_t time_to_read_data;
-std::size_t time_to_copy_data;
+double time_to_write_data;
+double time_to_read_data;
+double time_to_copy_data;
 
 oss << "WaveForm_data::get_waveform_data( ) -> ENTERING ..." << std::endl;