wat is the meaning of K=0 in root locus method

[sridhara]

we all know that root locus method is obtained by varying gain K from zero to infinity.....
my simple doubt
isnt K=0 meaningless since G(s) vanishes....

i would say K=0 is simply stated for mathematical purpose....am i right or wrong
correct me

 

[vacikel]

K=0 means you are seeing the roots of open loop system

you can check it with matlab plot a root locus with matlab and point the roots of open loop system with data curser you will see 'Gain=0'