mpicalc: 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/mpicalc - from package: libgcrypt20-dev

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

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