1.3.13. - Plotting and Data Analysis
spec's internal plotting and analysis facilities are currently limited to ASCII character plots on the screen or printer and operations such as finding the center and the full width at half maximum (FWHM) of a peak. The C-PLOT package provides most users with the sophisticated plotting and fitting capabilities that spec lacks.
Up to 8,192 pairs of points can be maintained by spec's plotting and analysis functions. The
pl_put(i, x, y)
function loads the
x
and
y
arguments into the element indexed by
i.
The
pl_xget(i)
and
pl_yget(i)
functions return the
x-value
or the
y-value
stored in position
i. Analysis is done using the
pl_anal(code)
function, which returns a value derived from the stored data according
to the value of
code.
For example,
pl_anal(5) returns the full width at half maximum of the peak.
See page ## in the
Reference Manual
for a complete description of the values returned by
pl_anal(). Typically, the inner loop of a scan calls
pl_put() for each data point.
The plotting macros then use the available analysis routines
to find the minimum and maximum of each axis and use
pl_xget() and
pl_yget() to plot each point.
The
plot_res,
rplot_res
and
splot_res
macros are defined to print the derived quantities such as
peak position, integrated intensity, etc.
in different contexts.