avpset——对avp参数进行初始化设置 function avp = avpset(att, vn, pos) ——`对avp进行初始化设置；输入参数att、vn和pos应都为列向量或行向量，最好都为列向量`% avp=[attitude; velocity; position] setting.%% Prototype: avp = avpset(att, vn, po