SpecTcl Spectra

	SpecTcl Spectra

Spectra are histograms of parameter sets. They are created and manipulated with the spectrum command. The following types of spectra are now supported in SpecTcl (as of version 0.4):

1d histograms: Histograms of the value of a single parameter. Channels can be either a word or a longword.
Bitmask histograms: For each bit in a parameter, the corresponding channel is incremented. Bitmask histograms are multiply incremented. Channels can be either a word or a longword.
1d Gamma histograms: Histograms on a set of parameters. The histogram is incremented for the value of each parameter. Gamma histograms are mutiply incremented. Channels can be either a word or a longword.
2d histograms: Histograms of an ordered pair of parameters. The first parameter selects the X coordinate and the second parameter the Y coordinate of the channel to increment for an event. A 2d histogram is only incremented if both parameters have been set by the event unpacker. The channels of a 2d histogram can be either a word or a byte.
Summary Spectra: 2d histograms which are useful for looking at an array of similar detectors. Summary spectra depend on an arbitrary number of parameters. The X coordinate of a summary spectrum increment is selected by the position of the parameter in the list the spectrum depends on. The Y coordinate of the increment, by the parameter value. Spectra can be multiply incremented (as many times as once per dependent parameter). Channels in a summary spectrum can be either word or byte.
2d Gamma histograms: These defined on an arbitrary number of parameters (more than 1). Each pair of parameters is taken as an ordered pair and the corresponding channel is incremented as for a 2d histogram. These histograms are multiply incremented. The channels of a histogram can be either a word or a byte.

Spectrum increment can be conditionalized by a gate. Spectra can be written to file using the swrite command and read in via the sread command.

Spectra can also be told what values to use as the upper and lower limits of their axes, as well as an arbitrary number of channels to display.