Zero Crossing Rate

Calculates the Zero Crossing Rate for a array of values, work for vector and matrix

Zero Crossing Rate
Works for vector and matrix
Vectorized function,very fast

if x is a Vector returns the zero crossing rate of the vector
Ex: x = [1 2 -3 4 5 -6 -2 -6 2];
y = ZCR(x) -> y = 0.444

if x is a matrix returns a row vector with the zero crossing rate of
the columns values

By: Jose Ricardo Zapata
Universidad Pontificia Bolivariana
2010