Chirp z-Transform

chirpz(v, lo, hi, d) Returns the frequency spectrum of the signal v between lo and hi at frequency intervals of d.

Arguments:

• v is a real- or complex-valued array.
• lo and hi are positive, real values for the endpoints of the frequency range. They are normalized so the sampling frequency is 1. hi is never greater than 0.5.
• d is a positive real frequency step size, such that (hi - lo)/d is at least 2.

Note:

• chirpz takes the FFT of an array with length of the original input signal plus the number of points in the interpolated spectrum minus one.

• If the total length of the array delivered to the FFT is prime or has few factors, this calculation will be slow.