DEF FPa1(T,Dj,G1,Nm,Sa1,Sa2,X,Y)
        OPTION ANGLE degrees
!        LET W1=4*Sa2+4*Sa1*(1-COS(X/2)*COS(Y/2)+Dj/4)
!        LET W2=8*Sa1+4*Sa2*(1-COS(X/2)*COS(Y/2))
        LET Nms=Nm*(2*Sa1+Sa2)/3
        LET COM=COS(X/2)*COS(Y/2)
        LET W1=4*Sa2+4*Sa1*(1-COM+G1*Dj/4)-Nms
        LET W2=8*Sa1+4*Sa2*(1-COM)-Nms
        LET W3=Sqr((W1-W2)^2+8*4*Sa1*Sa2*(COS(X/2)+COS(Y/2))^2)
        LET Wp=0.5*(W1+W2+W3)
        LET Wm=0.5*(W1+W2-W3)
        LET A1=(W1-Wm)/W3
        LET A2=(Wp-W1)/W3
LET FPa1=0.5*(1/(exp(W1/T)-1)+A1/(exp(Wp/T)-1)+A2/(exp(Wm/T)-1))
         
    END DEF
这是用true basic 编写的一个函数，请问大侠第二行OPTION ANGLE degrees语句是什么意思，十分感谢！！[em2]