//stability of open loop systems
s=%s
sys1=syslin('c',20/((s+1)*(s+2)*(s+3)))
disp(sys1,"M(s)=")
printf("sys1 is stable as there are no ploes or zeroes in RHP")
sys2=syslin('c',20*(s+1)/((s-1)*(s^2+2*s+2)))
disp(sys2,"M(s)=")
printf("sys2 is unstable due to pole at s=1")
sys3=syslin('c',20*(s-1)/((s+2)*(s^2+4)))
disp(sys3,"M(s)=")
printf("sys3 is marginally stable or marginally unstable due to s=j2 and s=-j2")
sys4=syslin('c',10/((s+10)*(s^2+4)^2))
disp(sys4,"M(s)=")
printf("sys4 is unstable due to multiple order pole at s=j2 and s=-j2")
sys5=syslin('c',10/(s^4+30*s^3+s^2+10*s))
disp(sys5,"M(s)=")
printf("sys5 is stable if pole at s=0 is placed intentionally")