i have discrete exponential function:x=exp(j*2*pi*t) that 't' is input time whit 2 series ex : t1=[30 60 90 120 .... 300] interval=30 t2=[50 100 150 200 250 300 ... 500] interval=50; t=sort[t1 t2] i want to find this two frequencies(=1/interval) whit fft but one frequency that not equal with this two frequency is detected.please help me. thanks