Question

用 matlab解微分方程组 意外地出现了 复数的结果

function dx=offset_angle_2(t,x)global d c0 k0 k11 k22 c w r m1 m2 D R01 R02 a yy R01=sqrt(r^2*(cos(yy)-r*cos(yy)/sqrt((r*cos(yy))^2+(d+r*sin(yy))^2))^2+(D+r*(sin(yy)-sin(yy)*cos(a))*sin(a))^2+(r*sin(yy)-(r*sin(yy)+(r*sin(yy)-r*sin(yy)*cos(a))*cos(a))+d)^2);R02=sqrt(r^2*(cos(yy+pi)-r*cos(yy+pi)/sqrt((r*cos(yy+pi))^2+(d+r*sin(yy+pi))^2))^2+(D+r*(sin(yy+pi)-sin(yy+pi)*cos(a))*sin(a))^2+(r*sin(yy+pi)-(r*sin(yy+pi)+(r*sin(yy+pi)-r*sin(yy+pi)*cos(a))*cos(a))+d)^2);dx=zeros(12,1);dx(1)=x(2);dx(3)=x(4); x(5)=x(1)*cos(y1(t))-x(3)*cos(y1(t)-a)-S1(t);dx(5)=x(6); x(7)=x(1)*cos(y2(t))-x(3)*cos(y2(t)-a)-S2(t);dx(7)=x(8); x(9)=x(3)*cos(y1(t)-a)+S1(t)-x(1)*cos(y1(t));dx(9)=x(10); x(11)=x(3)*cos(y2(t)-a)+S2(t)-x(1)*cos(y2(t));dx(11)=x(12);dx(2)=-(c0*x(2)+k0*x(1)+k1(t)*kk1(t)*cos(y1(t))+k2(t)*kk2(t)*cos(y2(t))+c*x(6)*cos(y1(t))+c*x(8)*cos(y2(t)))/m1;dx(4)=-(c0*x(4)+k0*x(3)+k3(t)*kk3(t)*cos(y1(t)-a)+k4(t)*kk4(t)*cos(y2(t)-a)+c*x(10)*cos(y1(t)-a)+c*x(12)*cos(y2(t)-a))/m2;function s=R1(t)s=sqrt(r^2*(cos(w*t+yy)-cos(b1(t)))^2+(D+s1(t))^2+(r*sin(w*t+yy)-l1(t)+d)^2);endfunction s=R2(t)s=sqrt(r^2*(cos(w*t+yy+pi)-cos(b2(t)))^2+(D+s2(t))^2+(r*sin(w*t+yy+pi)-l2(t)+d)^2);endfunction s=b1(t)s=atan((r*sin(w*t+yy)+d)/(r*cos(w*t+yy)));endfunction s=b2(t)s=atan((r*sin(w*t+yy+pi)+d)/(r*cos(w*t+yy+pi)));endfunction s=S1(t)s=R1(t)-R01;endfunction s=S2(t)s=R2(t)-R02;endfunction s=y1(t)s=acos(D+s1(t)/R1(t));endfunction s=y2(t)s=acos(D+s2(t)/R2(t));endfunction s=s1(t)s=r*(sin(w*t+yy)-sin(yy)*cos(a))*sin(a); endfunction s=s2(t)s=r*(sin(w*t+yy+pi)-sin(yy+pi)*cos(a))*sin(a);endfunction s=l1(t)s=r*sin(yy)+(r*sin(w*t+yy)-r*sin(yy)*cos(a))*cos(a);endfunction s=l2(t)s=r*sin(yy+pi)+(r*sin(w*t+yy+pi)-r*sin(yy+pi)*cos(a))*cos(a);endfunction s=kk1(t)s=x(1)*cos(y1(t))-S1(t)-x(3)*cos(y1(t)-a); endfunction s=kk2(t)s=x(1)*cos(y2(t))-S2(t)-x(3)*cos(y2(t)-a); endfunction s=kk3(t)s=x(3)*cos(y1(t)-a)+S1(t)-x(1)*cos(y1(t)); endfunction s=kk4(t)s=x(3)*cos(y2(t)-a)+S2(t)-x(1)*cos(y2(t));end function s=k1(t) if kk1(t)>=0 s=k11; else s=3*k11; end endfunction s=k2(t) if kk2(t)>=0 s=k22; else s=3*k22; endendfunction s=k3(t) if kk3(t)>=0 s=k11; else s=3*k11; endend function s=k4(t) if kk4(t)>=0 s=k22; else s=3*k22; end endend
源m文件如上
运行后出现如下提示
不知道是哪个步骤的运算出现了复数

Answer 1

1、p1~p8的具体数据是多少？
2、程序中有多处用到sqrt、acos函数，都可能导致出现复数。
3、对于这种不知道在哪个步骤出现复数的情况，最直接的做法是设置断点，跟踪程序的运行。