m_circle - M-circle plot
m_circle is used with nyquist.
//Example 1 :
s=poly(0,'s')
h=syslin('c',(s^2+2*0.9*10*s+100)/(s^2+2*0.3*10.1*s+102.01))
nyquist(h,0.01,100,'(s^2+2*0.9*10*s+100)/(s^2+2*0.3*10.1*s+102.01)')
m_circle();
//Example 2:
xbasc();
h1=h*syslin('c',(s^2+2*0.1*15.1*s+228.01)/(s^2+2*0.9*15*s+225))
nyquist([h1;h],0.01,100,['h1';'h'])
m_circle([-8 -6 -4]);