So, here is now a simplified test case. The polynomial poly is in reality much more complicated:
function poly=poly(la, lb, lc, Ia, Ib, Ic, RC)
poly=[1 la+lb*RC*45*la.^7 lb+lc-RC-3*Ib*Ic Ia*RC+Ib+87*RC Ib*Ic.^3+Ic/(Ia+Ic-la) RC-Ia*Ia*lc la*RC*Ib+Ia*RC la-lb*lc+Ia*Ib/RC+(la.^2*lb*lc-Ia)]
endfunction
function domi=dominant2(ns)
anfang=time();
if ( real(ns(1))>=real(ns(2)) & real(ns(1))>=real(ns(3)) & real(ns(1))>=real(ns(4)) & real(ns(1))>=real(ns(5)) & real(ns(1))>=real(ns(6)) & real(ns(1))>=real(ns(7)) )
domi=real(ns(1))+abs(imag(ns(1)))*i
else if (real(ns(2))>=real(ns(1)) & real(ns(2))>=real(ns(3)) & real(ns(2))>=real(ns(4)) & real(ns(2))>=real(ns(5)) & real(ns(2))>=real(ns(6)) & real(ns(2))>=real(ns(7)))
domi=real(ns(2))+abs(imag(ns(2)))*i
else if (real(ns(3))>=real(ns(1)) & real(ns(3))>=real(ns(2)) & real(ns(3))>=real(ns(4)) & real(ns(3))>=real(ns(5)) & real(ns(3))>=real(ns(6)) & real(ns(3))>=real(ns(7)) )
domi=real(ns(3))+abs(imag(ns(3)))*i
else if( real(ns(4))>=real(ns(1)) & real(ns(4))>=real(ns(2)) & real(ns(4))>=real(ns(3)) & real(ns(4))>=real(ns(5)) & real(ns(4))>=real(ns(6)) & real(ns(4))>=real(ns(7)) )
domi=real(ns(4))+abs(imag(ns(4)))*i
else if (real(ns(5))>=real(ns(1)) & real(ns(5))>=real(ns(2)) & real(ns(5))>=real(ns(3)) & real(ns(5))>=real(ns(4)) & real(ns(5))>=real(ns(6)) & real(ns(5))>=real(ns(7)) )
domi=real(ns(5))+abs(imag(ns(5)))*i
else if (real(ns(6))>=real(ns(1)) & real(ns(6))>=real(ns(2)) & real(ns(6))>=real(ns(3)) & real(ns(6))>=real(ns(4)) & real(ns(6))>=real(ns(5)) & real(ns(6))>=real(ns(7)) )
domi=real(ns(6))+abs(imag(ns(6)))*i
else if ( real(ns(7))>=real(ns(1)) & real(ns(7))>=real(ns(2)) & real(ns(7))>=real(ns(3)) & real(ns(7))>=real(ns(4)) & real(ns(7))>=real(ns(5)) & real(ns(7))>=real(ns(6)))
domi=real(ns(7))+abs(imag(ns(7)))*i
endif