Programmer Guide/Command Reference/EVAL/zcross: Difference between revisions

Revision as of 12:06, 11 April 2011

Compute zero crossing density.

Usage

qinterp(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 x[i] = f(i). The returned result is a scalar depending on 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

@@ Line 3: / Line 3: @@
 ;Usage:
-:<code>qinterp(<var>x</var> {<var>type</var>, {, <var>sr</var>}})</code>
+:<code>qinterp(<var>x</var> {<var>type</var> {, <var>sr</var> {, <var>xth</var>}}})</code>
 :;<var>x</var>:data vector (signal)
 :;<var>type</var>:selects the type of result; 0 <= ''type'' <= 3 (default=0)
 :;<var>sr</var>: sampling rate in Hz (default=1)
+:;<var>xth</var>: 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 <code>''x''[i] = f(i)</code>. The returned result is a scalar depending on ''z'' and the argument ''type''.
 :{|class="einrahmen"