$Id$
NeSDaC
range syntax
NAME
range and area syntax.
DESCRIPTION
StageII programs have parameter types specifying a range of values,
eg. select events in a time interval or within a range of energy-channels.
Given a range value, with a lower bound p and an upper bound q,
and a length L= p-q for real and L=p-q+1 for integral data.
The data-type of boundary values depends on the internal interpretation of
the data, not on the format, eg. presence or absence of a decimal point,
wherein you cast the numbers.
A range can be specified in one of the formats
p-q
p : L
p
Several ranges can be specified in a comma separated list
p0-q0,p1-q1, ...
The data-type of boundary values depends on the internal interpretation of
the data, not on the format, eg. presence or absence of a decimal point,
wherein you cast the numbers.
The format listed last (p)is an abbrevation for p-p, this does not make sense
for a real valued interval, as it will have zero length.
This abbrevation was introduced to facilitate the selection of integral values, eg.
a combination a energy-channel numbers.
The value for an area parameter consists of two ranges, glued together by a
: (colon).
The ranges apply respectively to the first axis (x) and second axis (y) lengths of
the (rectangular) area. The area value may be preceeded by a letter (i or x),
to emphasize the intended meaning, include or exclude items in the area.
Parameters with this type usually are used to select or reject certain sections
in the formation or destruction of an image.
Again several values may be chained in a comma separated list.
Example.
- the timerange variable 200:300,700-800 covers a timeinterval from
200 up to 500 (say) seconds, then skips time till 700, again covering the interval
up to 800 sec.
- 2,5,9,12 (short for 2-2,5-5,9-9,12-12,
or equivalently 2:1,5:1,9:1,12:1) selects a number of points from an
integer variable, eg. the energy-channel.
- x0-x1:y0-y1,x2-x3:y2-y3 select the union of the area's [x0,y0]-[x1,y1] and
[x2,y2]-[x3,y3] (points are 'lower-left' and 'upper-right' corner respectively).
- x660:20:660-680 from some process, exclude the area [660,660]-[680,680].
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