EdgeStats

EdgeStats [/A=avgPts /B=box /F=frac /L=(startLevel, endLevel ) /P /Q /R=(startX, endX ) /T=dx ] waveName

The EdgeStats operation produces simple statistics on a region of a wave that is expected to contain a single edge. If more than one edge exists, EdgeStats works on the first edge it finds.

Flags

/A=avgPts	Determines startLevel and endLevel automatically by averaging avgPts points at centered at startX and endX. Default is /A=1.
/B=box	Sets box size for sliding average. This should be an odd number. If /B=box is omitted or box equals 1, no averaging is done.
/F=frac	Specifies levels 1, 2 and 3 as a fraction of (endLevel -startLevel ):
	level1 = frac * (endLevel - startLevel ) + startLevel
	level2 = 0.5 * (endLevel - startLevel ) + startLevel
	level3 = (1 - frac ) * (endLevel - startLevel ) + startLevel
	The default value for frac is 0.1 which makes level1 the 10% level, level2 the 50% level and level3 the 90% level.
	frac must be between 0 and 0.5.
/L=(startLevel, endLevel)
	Sets startLevel and endLevel explicitly. If omitted, they are determined automatically. See /A.
/P	Output edge locations (see below) are returned in terms of point number. If /P is omitted, edge locations are returned in terms of X values.
/Q	Prevents results from being printed in history and prevents error if edge is not found.
/R=(startX,endX)	Specifies an x range of the wave to search. You may exchange startX and endX to reverse the search direction.
/R=[startP,endP]	Specifies a point range of the wave to search. You may exchange startP and endP to reverse the search direction. If /R is omitted, the entire wave is searched.
/T=dx	Forces search in two directions for a possibly more accurate result. dx controls where the second search starts.

Details

The /B=box, /T=dx, /P and /Q flags behave the same as for the FindLevel operation.

EdgeStats considers a region of the input wave between two X locations, called startX and endX. startX and endX are set by the /R=(startX,endX) flag. If this flag is missing, startX and endX default to the start and end of the entire wave. startX can be greater than endX so that the search for an edge can proceed from the "right" to the "left".

The diagram above shows the default search direction, from the "left" (lower point numbers) of the wave toward the "right" (higher point numbers).

The startLevel and endLevel values define the base levels of the edge. You can explicitly set these levels with the /L=(startLevel, endLevel) flag or you can let EdgeStats find the base levels for you by using the /A=avgPts flag which averages points around startX and endX.

Given startLevel and endLevel and a frac value (see the /F=frac flag) EdgeStats defines level1, level2 and level3 as shown in the diagram above. With the default frac value of 0.1, level1 is the 10% point, level2 is the 50% point and level3 is the 90% point.

With these levels defined, EdgeStats searches the wave from startX to endX looking for level2. Having found it, it then searches for level1 and level3. It returns results via variables described below.

EdgeStats sets the following variables:

V_flag	0: All three level crossings were found. 1: One or two level crossings were found. 2: No level crossings were found.
V_EdgeLoc1	X location at which level1 was found.
V_EdgeLoc2	X location at which level2 was found.
V_EdgeLoc3	X location at which level3 was found.
V_EdgeLvl0	startLevel value.
V_EdgeLvl1	level1 value.
V_EdgeLvl2	level2 value.
V_EdgeLvl3	level3 value.
V_EdgeLvl4	endLevel value.
V_EdgeAmp4_0	Edge amplitude (endLevel - startLevel )
V_EdgeDLoc3_1	Edge width (x distance between point 1 and point 3)
V_EdgeSlope3_1	Edge slope (straight line slope from point 1 to point 3)

These X locations and distances are in terms of the X scaling of the named wave unless you use the /P flag, in which case they are in terms of point number.

The EdgeStats operation is not multidimensional aware. See Multidimensional Waves, particularly Analysis on Multidimensional Waves for details.

See Also

FindLevel about the /B=box, /T=dx, /P and /Q flags, and PulseStats.