Given X with sampling rate Ft Hz and is used to generate another sequence Y with sampling rate Ft' Hz, then Sampling Rate ratio R is given by,

Ft'
R = ----
Ft

if R > 1, sampling process is known as interpolation
R < 1, sampling process is known as decimation

Example Usage:
t = 1:1/10:2;
X = sin (2 * pi * 10 * t) % 10 Hz sine wave
N = 3 % Interpolation/Decimation factor
Y = sample (X, N, 'UP')