matlab高手求助,Conversion to double from sym is not possible.

matlab高手求助,Conversion to double from sym is not possible.
syms l;
syms t;
syms Ommiga_0;
syms Ommiga_3;
syms d;
syms tau;
syms ommiga_1;
syms ommiga_3;
syms U_0;
k_1=pi/2/l;
k_3=3*pi/2/l;
k_2=2*pi/2/l;
g=9.8
ommiga_1=sqrt(g*k_1*tanh(k_1)*d);
ommiga_3=sqrt(g*k_3*tanh(k_3)*d);
A_1=2*Ommiga_0*U_0*(Ommiga_0*sin(Ommiga_0*tau)-ommiga_1*sin(ommiga_1*tau))/k_1^2/l/(ommiga_1^2-Ommiga_0^2);
A_3=2*Ommiga_0*U_0*(Ommiga_0*sin(Ommiga_0*tau)-ommiga_3*sin(ommiga_3*tau))/k_3^2/l/(ommiga_3^2-Ommiga_0^2);
B_1=2*ommiga_1*U_0*(ommiga_1*sin(Ommiga_0*tau)-Ommiga_0*sin(ommiga_1*tau))/k_1^2/l/(ommiga_1^2-Ommiga_0^2);
B_3=2*ommiga_3*U_0*(ommiga_3*sin(Ommiga_0*tau)-Ommiga_0*sin(ommiga_3*tau))/k_3^2/l/(ommiga_3^2-Ommiga_0^2);
C_1=2*Ommiga_0*U_0*(Ommiga_0^2*cos(Ommiga_0*tau)-ommiga_1^2*cos(ommiga_1*tau))/k_1^2/l/(ommiga_1^2-Ommiga_0^2);
C_3=2*Ommiga_0*U_0*(Ommiga_0^2*cos(Ommiga_0*tau)-ommiga_3^2*cos(ommiga_3*tau))/k_3^2/l/(ommiga_3^2-Ommiga_0^2);
D_1=2*ommiga_1*U_0*(Ommiga_0*ommiga_1*cos(Ommiga_0*tau)-Ommiga_0*ommiga_1*cos(ommiga_1*tau))/k_1^2/l/(ommiga_1^2-Ommiga_0^2);
D_3=2*ommiga_3*U_0*(Ommiga_0*ommiga_3*cos(Ommiga_0*tau)-Ommiga_0*ommiga_3*cos(ommiga_3*tau))/k_3^2/l/(ommiga_3^2-Ommiga_0^2);
Q_2=0.5*(-D_3*A_1*k_3*k_1+D_3*B_1*k_1^2+(A_3*D_1*k_3*tanh(k_3*d)+A_1*D_3*k_1*tanh(k_1*d))-0.5*(C_3*A_1+A_3*C_1)*k_3*k_1*(1+tanh(k_3*d)*tanh(k_1*d)))...
+0.5*(-D_1*A_3*k_1*k_3+D_1*B_3*k_3^2+(A_1*D_3*k_1*tanh(k_1*d)+A_3*D_1*k_3*tanh(k_3*d))*k_3*tanh(k_3*d)-0.5*(C_1*A_3+A_1*C_3)*k_1*k_3*(1+tanh(k_1*d)*tanh(k_3*d)))...
+0.5*(D_1*A_1*k_2*k_1+D_1*B_1*k_1^2+(A_1*D_1*k_1*tanh(k_1*d)+A_1*D_1*k_1*tanh(k_1*d))*k_1*tanh(k_1*d)-C_1*A_1*k_1^2*(-1+tanh(k_1*d)*tanh(k_1*d)));
C_2=int(Q_2,tau,0,t);
t=(0:100);
plot(t,C_2)

你要画图,意味着需要具体的数据.而你前面的符号运算没法得到具体数据.问题的关键就在这里.给你修改了下,其中具体参数需要你自己补足!
clear;
clc;
close all;
syms tau real;
l = 1 ;
d = 1 ;
Ommiga_0 = 1 ;
U_0 = 1 ;
k_1=pi/2/l;
k_3=3*pi/2/l;
k_2=2*pi/2/l;
g=9.8;
ommiga_1=sqrt(g*k_1*tanh(k_1)*d);
ommiga_3=sqrt(g*k_3*tanh(k_3)*d);
A_1=2*Ommiga_0*U_0*(Ommiga_0*sin(Ommiga_0*tau)-ommiga_1*sin(ommiga_1*tau))/k_1^2/l/(ommiga_1^2-Ommiga_0^2);
A_3=2*Ommiga_0*U_0*(Ommiga_0*sin(Ommiga_0*tau)-ommiga_3*sin(ommiga_3*tau))/k_3^2/l/(ommiga_3^2-Ommiga_0^2);
B_1=2*ommiga_1*U_0*(ommiga_1*sin(Ommiga_0*tau)-Ommiga_0*sin(ommiga_1*tau))/k_1^2/l/(ommiga_1^2-Ommiga_0^2);
B_3=2*ommiga_3*U_0*(ommiga_3*sin(Ommiga_0*tau)-Ommiga_0*sin(ommiga_3*tau))/k_3^2/l/(ommiga_3^2-Ommiga_0^2);
C_1=2*Ommiga_0*U_0*(Ommiga_0^2*cos(Ommiga_0*tau)-ommiga_1^2*cos(ommiga_1*tau))/k_1^2/l/(ommiga_1^2-Ommiga_0^2);
C_3=2*Ommiga_0*U_0*(Ommiga_0^2*cos(Ommiga_0*tau)-ommiga_3^2*cos(ommiga_3*tau))/k_3^2/l/(ommiga_3^2-Ommiga_0^2);
D_1=2*ommiga_1*U_0*(Ommiga_0*ommiga_1*cos(Ommiga_0*tau)-Ommiga_0*ommiga_1*cos(ommiga_1*tau))/k_1^2/l/(ommiga_1^2-Ommiga_0^2);
D_3=2*ommiga_3*U_0*(Ommiga_0*ommiga_3*cos(Ommiga_0*tau)-Ommiga_0*ommiga_3*cos(ommiga_3*tau))/k_3^2/l/(ommiga_3^2-Ommiga_0^2);
Q_2=0.5*(-D_3*A_1*k_3*k_1+D_3*B_1*k_1^2+(A_3*D_1*k_3*tanh(k_3*d)+A_1*D_3*k_1*tanh(k_1*d))-0.5*(C_3*A_1+A_3*C_1)*k_3*k_1*(1+tanh(k_3*d)*tanh(k_1*d)))...
+0.5*(-D_1*A_3*k_1*k_3+D_1*B_3*k_3^2+(A_1*D_3*k_1*tanh(k_1*d)+A_3*D_1*k_3*tanh(k_3*d))*k_3*tanh(k_3*d)-0.5*(C_1*A_3+A_1*C_3)*k_1*k_3*(1+tanh(k_1*d)*tanh(k_3*d)))...
+0.5*(D_1*A_1*k_2*k_1+D_1*B_1*k_1^2+(A_1*D_1*k_1*tanh(k_1*d)+A_1*D_1*k_1*tanh(k_1*d))*k_1*tanh(k_1*d)-C_1*A_1*k_1^2*(-1+tanh(k_1*d)*tanh(k_1*d)));
t=(0:100)';
for i=1:length(t)
C_2(i) = double(int(Q_2,'tau',0,t(i)));
end
plot(t,C_2)