12 #ifndef MLPACK_CORE_UTIL_LOWER_STRING_HPP    13 #define MLPACK_CORE_UTIL_LOWER_STRING_HPP    23 inline std::string 
ToLower(
const std::string& input)
    26   std::transform(input.begin(), input.end(), std::back_inserter(output),
    27       [](
unsigned char c){ 
return std::tolower(c); });
 Linear algebra utility functions, generally performed on matrices or vectors. 
 
std::string ToLower(const std::string &input)
Convert a string to lowercase letters.