SUMMARY

Controls the "quick and dirty plot" option.

SYNTAX

QDP {ON|OFF|n},{TERM ON|OFF|n},{SGF ON|OFF|n}

INPUT

ON:	Turn QDP option on for both the terminal and SAC Graphics File (SGF) devices.
OFF:	Turn QDP option off for both devices.
n:	Turn QDP option on for both devices and change the approximate number of data points to plot to n.
TERM ON:	Turn quick and dirty plotting on for the terminal.
TERM OFF:	Turn quick and dirty plotting off for the terminal.
TERM n:	Turn QDP option on for the terminal and change the approximate number of data points to plot to n.
SGF ON:	Turn quick and dirty plotting on for the SGF.
SGF OFF:	Turn quick and dirty plotting off for the SGF.
SGF n:	Turn QDP option on for the SGF and change the approximate number of data points to plot to n.

DEFAULT VALUES

QDP TERM 5000 SGF 5000

DESCRIPTION

Plotting large files (greater than say 1000 points) can take a long time. The "quick and dirty plot" option speeds up plotting by NOT plotting each data point. When this option is on, SAC will compute a section size by dividing the number of data points in the file by the number of data points you want displayed. The larger the file, the more data points in each section.

SAC then computes and displays only the minimum and the maximum data point in each section. SAC displays a "desampling factor" (half the section size) in a small box in the corner of the plot when this option is on. Displayed data points may be somewhat closer or further apart than this number indicates since the extremum in each region are being plotted.

There is a separate QDP option for the terminal and the SAC Graphics File device. The terminal QDP factor also applies to the XWINDOWS and SUNWINDOWS graphics devices. By default the QDP factor is considerably smaller for the terminal than for the SGF. This allows for very fast plots to the terminal and a more representative plot to the SGF. If both devices are on at the same time, the terminal QDP option applies. You may turn either of these options off or change the number of displayed points.

EXAMPLES

Assume FILE1 has 2100 data points and FILE2 has 4700 data points. If you typed:

SAC> READ FILE1 FILE2
SAC> BEGINDEVICES TERMINAL
SAC> PLOT

both plots would contain approximately 200 data points. The plot of FILE1 would contain approximately every tenth data point and the plot of FILE2 every twenty-third data point. The section size is rounded down to ensure that you will see at least the number of requested data points. If you now plotted those same files to the SGF:

SAC> BEGINDEVICES SGF
SAC> PLOT

both plots would contain approximately 1000 data points. If both devices were on, the plots would contain approximately 200 data points, the factor for the terminal.

LATEST REVISION

February 20, 1985 (Version 9.13)