# zcross

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Compute zero crossing density.

- Usage
`zcross(`

`x`{`type`{,`sr`{,`xth`}}})`x`- data vector (signal)
`type`- selects the type of result; 0 ≤
*type*≤ 3 (default=0) `sr`- sampling rate in Hz (default=1)
`xth`- threshold value (default=0); if
*xth*is a value greater than 0, fluctuations of the function in the range*-xth*<*x*[i] <*xth*are ignored

- Result
- The function counts the number of zero crossings
*z*of the function

. The returned result is a scalar depending on*x*[i] = f(i)*z*and the argument*type*.

*type*description result **0**the number of zero crossing *z***1**the zero crossing density

(number of zero crossings / second)*d*=*z*/ (**ncol**(*x*) **sr*)**2**the average zero crossing frequenzy (in Hz) *f*=*d*/ 2**3**the average zero crossing periode length (in seconds) *t*= 1 /*f*= 2 /*d*

- See also
- f0ac