Kerboscript stageISP calculator

FUNCTION stageISP {
    DECLARE thrustTotal IS 0.
    DECLARE mDotTotal IS 0.
    DECLARE avgISP IS 0.
    LIST ENGINES IN engList.
    FOR eng IN engList {
        IF eng:IGNITION {
            LOCAL t IS eng:MAXTHRUST*eng:thrustlimit/100.
            SET thrustTotal to thrustTotal + t.
            IF eng:VISP = 0 {
                SET mDotTotal to 1.
            }.
            ELSE {
                SET mDotTotal to mDotTotal + t / eng:ISP.
            }.
        }.
    }.
    IF mDotTotal = 0 {
         SET avgISP TO 0.
    } ELSE {
        SET avgISP TO thrustTotal/mDotTotal.
    }

    return avgISP.
}