SATAN Help
DATA TYPES, MODES AND FORMATS
TYPES
Numbers may be defined using the following types:
FIXED (INTEGER) -> Integer numbers with 2 or 4 bytes and
(declaration in PL/I: Bin Fixed(15) or Bin Fixed(31) )
FLOAT (REAL) -> Floating-point numbers with 4 or 8 bytes
(declaration in PL/I: Dec Float(6) or Dec Float(16) ).
MODES
Spectra may be defined using the following modes:
DIGITAL -> y values represent the weights of discrete x values.
Digital data are represented by a data symbol and/or a connecting line.
Digital analyzers are
defined by the command AGEN or the macro AGEN when chosing the option
MODE(DIGITAL).
Command AGEN: AGEN /
MODE(DIGITAL)
Macro AGEN:
AGEN / MODE(DIGITAL)
The yields of a nuclear-charge distribution are
digital data, because the antomic number Z
is only defined for integer values.
ANALOG -> y values represent the contents of intervals (bins) of a density distribution
for continuous x values.
Analog data are represented by an histogram.
Analog analyzers are defined by the
command AGEN or the macro AGEN when chosing the option MODE(ANALOG).
Command AGEN:
AGEN / MODE(ANALOG)
Macro AGEN:
AGEN / MODE(ANALOG)
The angular distribution of reaction products are
analog data, because the angle may take any
value of a continuous distribution.
The "name" of a data bin is given by the lower limit of the bin. Thus, the mean
value of a data bin is the lower limit of the bin plus half the bin size.
When spectra are drawn as an histogram, they are interpreted as analog data, otherwise
they are considered to be digital data.
These remarks also refer to pseudoanalyzers. Look here examples
for a pseudoanalyzer with digital data and an example
for a pseudoanalyzer with analog data.
Spectra with analog data can be interpreted in two different ways;
1. COUNTS PER BIN
The content (y value of the spectrum) is taken as counts per bin.
If the counts in the spectrum are
governed
by Poisson statistics, the statistical
uncertainties are directly given by the square-root of the y values. This is an advantage
for practical applications. In this mode, however, the y values of a spectrum change if
the binsize is modified. Moreover, the content of a spectrum (sum of counts) does not
agree with its integral surface.
This option is the default for SATAN analyzers.
2. COUNTS PER CHANNEL
The content (y value of the spectrum) is taken as counts per channel,
or in other words as counts per one unit of the x axis.
In this mode, the content of a spectrum (sum of counts) agrees with its integral surface.
This is the mathematically more consistent option.
The two options may be chosen by the corresponding buttons of the SATAN interface or by
the command SET / HISTOGRAMMING(..)
or by the corresponding buttons on the SATAN Interface window.
Analog data in pseudoanalyzers are always interpreted as "counts per channel".
DATA FORMATS
GRAF data which are read from a dataset with the command GREAD
are generally interpreted as 4-byte floating-point numbers with 6 significant decimal
digits. Their range is limited (from 0.29E-38 to 1.7E38 on VMS).
Data of PSEUDOANALYZERS may be analog (if drawn as an
histogram) or digital (if drawn differently). They may have equidistant or non-equidistant
floating-point x values. (see HELP ANALYZERS)
ANALYZER data (y values) may have 4-byte FIXED or 4-byte FLOAT type.
Only equidistant x values are supported. The binsize may have any value.
Analyzers may be created by the macro AGEN (see HELP EXTEND), by the command AGEN or
by fetching pseudoanalyzers from a dataset (command AFETCH).
AFETCH supports GRAF format and GEF format.
