How to plot the solution?

clc
close all
syms L
e = exp(sym(1));
lags = 0;
k1 = 3;
k_1 = 1;
k2 = 2.5;
k3 = 1;
k_3 = 1;
k4 = 2;
k5 = 1;
E1 = 1;
E2 = 2;
K1 = (k_1+k2)/k1;
K2 = (k_3+k4)/k3;
a = -(k5*E1)^2;
b = -k3*E2-(k5*E1)^(2)*(k_1+k_3+k2+k4+k1*E1);
c = k3*E2*(k_1+k2+k4+k1*E1)+(k5*E1)^(2)*(k1*k2*E1+(k_3+k4)*(k_1+k2+k1*E1));
d = k3*E2*k4*(k_1+k2)+k1*k3*E1*E2*(k2+k4)+k1*k2*k5^2*E1^3*(k_3+k4);
h = k5*E1;
f = k5*E1*(k_1+k_3+k2+k4+k3*E2);
g = k5*E1*(k_1+k2)*(k_3+k2+k3*E2);
eqn = (a*L^3+b*L^2-c*L-d)-(h*L^2+f*L+g)*e^(-L*lags);
vpasolve(eqn)

ans = 

[Torsten]

What do you want to plot ? At the moment, you only have three single numbers two of which are complex.

[Akhtar Jan]

i want to plot L vs. lags

[Torsten]

And what is the range of "lags" for which you want to determine L ?

[Akhtar Jan]

clc

close all

lags = 0;
k1 = 3;
k_1 = 1;
k2 = 2.5;
k3 = 1;
k_3 = 1;
k4 = 2;
k5 = 1;
E1 = 1;
E2 = 2;
K1 = (k_1+k2)/k1;
K2 = (k_3+k4)/k3;
a = -(k5*E1)^2;
b = -k3*E2-(k5*E1)^(2)*(k_1+k_3+k2+k4+k1*E1);
c = k3*E2*(k_1+k2+k4+k1*E1)+(k5*E1)^(2)*(k1*k2*E1+(k_3+k4)*(k_1+k2+k1*E1));
d = k3*E2*k4*(k_1+k2)+k1*k3*E1*E2*(k2+k4)+k1*k2*k5^2*E1^3*(k_3+k4);
h = k5*E1;
f = k5*E1*(k_1+k_3+k2+k4+k3*E2);
g = k5*E1*(k_1+k2)*(k_3+k2+k3*E2);
fun = @(L) (a*L.^3+b*L.^2-c*L-d)-(h*L.^2+f*L+g).*exp(-L*lags);
% replaced e^ with exp, changed ^2 with .^2, and * to .*
L0 = -1.5;
L1 = fsolve(fun,L0);
L0 = -2.5;
L2 = fsolve(fun,L0);
plot((-2.5:0.1:-1),fun(-2.5:0.1:-1))

% look at the above code it is same as the given code it can plot the solution 
% I need the same plot for my given code

[Walter Roberson]

http://www.mathworks.co.uk/matlabcentral/answers/43073-a-guide-to-tags

Answer 1

[Torsten]

syms L lags
e = exp(sym(1));
k1 = 3;
k_1 = 1;
k2 = 2.5;
k3 = 1;
k_3 = 1;
k4 = 2;
k5 = 1;
E1 = 1;
E2 = 2;
K1 = (k_1+k2)/k1;
K2 = (k_3+k4)/k3;
a = -(k5*E1)^2;
b = -k3*E2-(k5*E1)^(2)*(k_1+k_3+k2+k4+k1*E1);
c = k3*E2*(k_1+k2+k4+k1*E1)+(k5*E1)^(2)*(k1*k2*E1+(k_3+k4)*(k_1+k2+k1*E1));
d = k3*E2*k4*(k_1+k2)+k1*k3*E1*E2*(k2+k4)+k1*k2*k5^2*E1^3*(k_3+k4);
h = k5*E1;
f = k5*E1*(k_1+k_3+k2+k4+k3*E2);
g = k5*E1*(k_1+k2)*(k_3+k2+k3*E2);
eqn = (a*L^3+b*L^2-c*L-d)-(h*L^2+f*L+g)*e^(-L*lags);
lags_num = 0.01:0.01:0.18;
for i=1:numel(lags_num)
    L_num(i) = double(vpasolve(subs(eqn,lags,lags_num(i))));
end
plot(lags_num,L_num)

[Akhtar Jan]

Thank you sir ):-