Evans function invalid index error

Specific domains Modeling and simulation
1 
s = poly(0, 's');
n1=(s+2); 
d1=(s+3)(s^2+2*s+2); 
h1= syslin('c', n1,d1);
disp(h1);
evans(h1,50);

there is no error, but the graphic window number 0 is blank.

2

Hello,

The third line yields an error

--> s = poly(0, 's');

--> n1=(s+2); 

--> d1=(s+3)(s^2+2*s+2); 

Invalid index.

because you are missing a multiplication sign. By fixing it

s = poly(0, 's');
n1=(s+2); 
d1=(s+3)*(s^2+2*s+2); 
h1= syslin('c', n1,d1);
disp(h1);
evans(h1,50);

you get what you expected:
disc