seqperiod function error for complex data

z=[1+i, 2+3i, 1+i, 3+4i];

[r, num]= seqperiod(real(z)');

 [s, num]= seqperiod(imag(z)');

It returns r as 4 and num as 1. Same is coming for s.

But I expect r=2 and num=1

I need your help.