MATLAB: Different results with same code?

eigenvaluematrix

Please consider 2 scripts below, this supposed to be output the same results of D but it doesn't
script 1:
m_s = 2000;                        %(kg)   Sprung mass 

m_u = 200;                         %(kg)   Un-sprung mass

k_s = 200000;                      %(N/m)  Suspension stiffness
k_u = 870000;                      %(N/m)  Tire stiffness

c_s = 6000;                        %(Ns/m) Damping coefficient

M = [m_u 0;0 m_s];
K = [k_s+k_u -k_s; -k_s k_s];
A = M\K;
[V,D]  = eig(A); 
D
script 2:
m_s = 2000;                        %(kg)   Sprung mass 
m_u = 200;                         %(kg)   Un-sprung mass
k_u = 870000;                      %(N/m)  Tire stiffness
c_s = 6000;                        %(Ns/m) Damping coefficient
syms  k_s
M = [m_u 0;0 m_s];
K = [k_s+k_u -k_s; -k_s k_s];
A = M\K;
[V,D]   = eig(A);
k_s = 200000;
D=double(subs(D))
THANK YOU!

Best Answer

D=double(subs(D,k_s))
Use the variable k_s as argument, I get the same results now 
 m_s = 2000;                        %(kg)   Sprung mass 

m_u = 200;                         %(kg)   Un-sprung mass

k_s = 200000;                      %(N/m)  Suspension stiffness
k_u = 870000;                      %(N/m)  Tire stiffness

c_s = 6000;                        %(Ns/m) Damping coefficient

M = [m_u 0;0 m_s];
K = [k_s+k_u  -k_s; -k_s  k_s];
A = M\K;
[V,D]  = eig(A); 
D
D =
   1.0e+03 *
    5.3690         0
         0    0.0810      
clear
m_s = 2000;                        %(kg)   Sprung mass 
m_u = 200;                         %(kg)   Un-sprung mass
k_u = 870000;                      %(N/m)  Tire stiffness
c_s = 6000;                        %(Ns/m) Damping coefficient
syms  k_s
M = [m_u 0;0 m_s];
K = [k_s+k_u  -k_s; -k_s  k_s];
A = M\K;
[V,D]   = eig(A);
k_s = 200000;
D=double(subs(D,k_s))
D =
   1.0e+03 *
    5.3690         0 
      0    0.0810
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