rdbfwhm - calculate the FWHM from data in an rdb table
The rdb file in which the input data reside. If it is the string
stdin, it is read from the UNIX standard input stream. This is the default.
The destination for the output data (in the form of an rdb table). If it is
the string stdout, it is written to the UNIX standard output stream. This is the default.
The name of the column which contains the independent data. It defaults to x.
The name of the column which contains the dependent data. It defaults to y.
The name of the column which contains either the error in the dependent data, or the number of the number of events which went into the dependent data. If not specified, errors are not calculated.
If set, and if -q is specified, that column contains counts.
The algorithm use to determine the maximum point. It may be one of spline or raw. raw is the default. See below.
Print out rdbfwhm's version and exit.
Print out help and exit.
rdbfwhm reads data from an rdb file and calculates its full width half max (FWHM) and, optionally its error.
The input data set should have at least two columns for the independent and dependent variables. If errors are to be calculated, it should contain a column containing either the error on the dependent variable, or the number of events which went into its determination (assuming that the dependent value is a sum of weights, for instance). In the latter case, the -cnts option should be specified.
For instance, let's say that the dependent variable represents a flux; the error in the flux in each channel is dependent upon the number of photons that were measured in the channel. If the dependent variable is actually counts, just set q to the same name as y.
The maximum point is determined by one of several algorithms, as specified by the max_alg parameter:
The maximum input data value is used.
a spline interpolation is performed. The uncertainty in the interpolated maximum is determined by interpolating the q data at the determined position of the maximum.
Output is written as an rdb table, with columns fwhm,
fwhm_err, xmax (the value of the independet variable at which the peak is found), ymax the peak value. There is but one row.
D. Jerius ( djerius@cfa.harvard.edu )
$Id: rdbfwhm.pl,v 1.8 2000/03/23 08:07:17 dj Exp $