mlpack_decision_stump: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On Debian possible default full paths are:

/usr/bin/mlpack_decision_stump - from package: mlpack-bin

You may install the required package with command apt-get install {package}

Error in other languages:
mlpack_decision_stump: bevel nie gevind nie
mlpack_decision_stump: comandă negăsită
mlpack_decision_stump: comando não encontrado
mlpack_decision_stump: commande introuvable
mlpack_decision_stump: command not found
mlpack_decision_stump: käsku ei ole
mlpack_decision_stump: không tìm thấy lệnh
mlpack_decision_stump: komanda nerasta
mlpack_decision_stump: Kommando nicht gefunden.
mlpack_decision_stump: kommandot finns inte
mlpack_decision_stump: komut yok
mlpack_decision_stump: nie znaleziono polecenia
mlpack_decision_stump: níor aimsíodh an t-ordú
mlpack_decision_stump: no se encontró la orden
mlpack_decision_stump: no s'ha trobat l'ordre
mlpack_decision_stump: opdracht niet gevonden
mlpack_decision_stump: parancs nem található
mlpack_decision_stump: perintah tidak ditemukan
mlpack_decision_stump: príkaz nenájdený
mlpack_decision_stump: příkaz nenalezen
mlpack_decision_stump: команда не найдена
mlpack_decision_stump: командата не е открита
mlpack_decision_stump: 命令找不到
mlpack_decision_stump: コマンドが見つかりません