rmaxima: 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 CentOS possible default full paths are:

/usr/bin/rmaxima - from package: maxima

You may install the required package with command yum install {package}

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