Make one or more plots to the current plot device (see cpd or setplot device).
|Syntax:||plot||<plot type>[<plot type>] [<plot type>] ...|
<plot type> is a keyword describing the various plots allowed. Up to six plot panes can be put on a single page by combining multiple <plot type> options. For example:
XSPEC12> plot data resid ratio modelwill produce a 4-pane plot. However contour plots may not be combined with other plots in this manner. When a certain plot type takes additional arguments (eg. chain, model), simply list them in order prior to specifying the next plot type:
XSPEC12> plot chain 3 4 data ufspecIn multi-pane plots, XSPEC will determine if two consecutive plot types may share a common X-axis (e.g. plot data delchi, or plot counts ratio). If so, the first pane will be stacked directly on top of the second. (Note that the small subset of multi-pane plots that were allowed in earlier versions of XSPEC all belonged in this category.)
For changing plot units, see setplot energy and setplot wave. Also see iplot for performing interactive plots.
When plotting colors the ordering is from pgplot and is shown in Figure 5.1.
plot chain [thin <n>] [mean] [auto <n>] <par1>[<par2>]
Chains must be currently loaded (see chain command), and <par1> and <par2> are parameter identifiers of the form [<model name>:]<n> or for response parameters [<source number>:]r<n> where <n> is an integer, specifying the parameter columns in the chain file to serve as the X and Y axes respectively. To select the fit-statistic column, enter '0' for the <par> value. If <par2> is omitted, <par1> is simply plotted against row number.
Use the thin <n> option to display only 1 out of every <n> chain points. Example:
# plot one in five chain points, # using parameters 1 and 4 for (X,Y) plot chain thin 5 1 4The thin value will be retained for future chain plots until it is reset. Enter thin 1 to remove thinning.
Use the mean option to display the running mean based on all previous chain values instead of the chain value.
Use the auto <n> option to display the autocorrelation function for the chain where <n> is the number of lags to plot. auto cannot be used at the same time as mean and it will ignore the setting of thin. auto only uses one parameter identifier. For example:
plot chain auto 50 2
plot contour [<min fit stat>[<# levels>[<levels>]]]
where <min fit stat> is the minimum fit statistic relative to which the delta fit statistic is calculated, <# levels> is the number of contour levels to use and <levels> := <level1> ... <levelN> are the contour levels in the delta fit statistic. contour will plot the fit statistic grid calculated by the last steppar command (which should have gridded on two parameters). A small plus sign '+' will be drawn on the plot at the parameter values corresponding to the minimum found by the most recent fit.
The fit statistic confidence contours are often drawn based on a relatively small grid (i.e., 5x5). To understand fully what these plots are telling you, it is useful to know a couple of points concerning how the software chooses the location of the contour lines. The contour plot is drawn based only on the information contained in the sample grid. For example, if the minimum fit statistic occurs when parameter 1 equals 2.25 and you use steppar 1 1.0 5.0 4, then the grid values closest to the minimum are 2.0 and 3.0. This could mean that there are no grid points where delta-fit statistic is less than your lowest level (which defaults to 1.0). As a result, the lowest contour will not be drawn. This effect can be minimized by always selecting a steppar range that causes XSPEC to step very close to the true minima.
For the above example, using steppar 1 1.25 5.25 4, would have been a better selection. The location of a contour line between grid points is designated using a linear interpolation. Since the fit statistic surface is often quadratic, a linear interpolation will result in the lines being drawn inside the true location of the contour. The combination of this and the previous effect sometimes will result in the minimum found by the fit command lying outside the region enclosed by the lowest contour level.
A grey-scale image of the data being contoured is also plotted. This can be removed by using the PLT command image off.
XSPEC12> steppar 2 0.5 1. 4 3 1. 2. 4 // create a grid for parameters 2 and 3 XSPEC12> plot contour // Plot out a grid with three contours with // delta fit statistic of 2.3, 4.61 and 9.21 XSPEC12> plot cont,,4,1.,2.3,4.61,9.21 // same as above, but with a delta fit statistic = 1 contour.