[问题] 复数 X 和/或 Y 参数的虚部已忽略

[梨核儿]

在用for循环求解微分方程时，进行plot时，出现了“警告: 复数 X 和/或 Y 参数的虚部已忽略 ”，这个问题应该如何解决呢？
for t = t0:dt:tf
%d=-cos(pi*t); %外界扰动
u0 = pi/2*cos(t);
ksi = x-x0; % x_e
it = v-v0; % v_e

ind1=find((it.^(m1/n1-1))<=r);
ind2=find((it.^(m1/n1-1))>r);
delt(ind1)=sin(pi/2*abs(it.^(m1/n1-1)).^2/r^2);
delt(ind2)=1;
%%%%%%%%%%%%%%%%%%%%%%%%
s = sign(it)*abs(it^(m1/n1))+a1*sign(ksi)*abs(ksi^(m2/n2))+b1*sign(ksi)*abs(ksi^(m3/n3));
ds = delt*(a1*sign(s)*abs(s^(m2/n2))+b1*sign(s)*abs(s^(m3/n3)))^(n1/m1);
%ds = delt*(sign(-ksi)*abs(ksi^(1/3))-sign(-it)*(-it^3));
ind1=find(abs(s)<=sigma);
ind2=find(abs(s)>sigma);
epsilon(ind1)=x/sigma;
epsilon(ind2)=sign(s);
u = -(n1/m1)*(a1*m2/n2*ksi^(m2/n2-1)+b1*m3/n3*ksi^(m3/n3-1))*it^(2-m1/n1)-n1/m1*delt*it^(1-m1/n1)*(a1*s^(m2/n2)+b1*s^(m3/n3))^(n1/m1)-lammd*epsilon;
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
dx = v;
dv = u;
dx0 = v0;
dv0 = u0;

x = x+dx*dt;
v = v+dv*dt;
v0 = v0+dv0*dt;
x0 = x0+dx0*dt;
s = s+ds*dt;

u_mat=[u_mat,u];
u0_mat=[u0_mat,u0];
x_mat=[x_mat,x];
v_mat=[v_mat,v];
x0_mat=[x0_mat,x0];
ksi_mat=[ksi_mat,ksi];
it_mat=[it_mat,it];
v0_mat=[v0_mat,v0];
s_mat=[s_mat,s];
end