Plots

Using Plot Windows

The Plot Window you have created has several functions available from its pulldown menu, as shown in figure 15-3. The mouse pointer can also be used to directly spot a data point on the graph.

Figure 15-3: Plot Window Menu

Rescale the Plot

  1. Click LEFT on the graph to show a small cross. Then click LEFT again on the same graph, but on a different place to form a rectangle as shown in figure 15-4.
  2. Press LEFT on the window title to get a pulldown menu and release on Rescale Graph. This changes the graph upper and lower limits to the desired values, thus effectively zooming into the specified area.

    Figure 15-4: Rescale Rectangle

  3. To pan, click LEFT on the graph only once, then select Rescale Graph from the pulldown menu. This will change the scale to make the clicked point (small cross) the new center of the graph.

NOTE: To reset the graph scale back to the original, select Rescale Graph without having a rectangle on the graph, or select Replot Data.

Mark a Point

  1. Click MIDDLE on the graph. This identifies the nearest data point on the graph and shows its X and Y values and data point number, as shown in figure 15-5.
  2. Click MIDDLE in the graph window, but on the outside of the graph itself. This erases the circle that marks the point, as well as its data values.

    Figure 15-5: Marker in Plot

    The data point number has two digits separated by a slash. The number on the left of the slash represents the primary sweep point number (sweep order 1), and the number on the right shows the secondary sweep point number (sweep order 2). A data point on Y2 axis can not be identified.

Draw a Line

  1. Click LEFT on a curve and click LEFT again on the same curve, but on a different point. This shows the "Rescale Rectangle" again.
  2. press LEFT on the window title to get the pulldown menu, and release on Draw Diag Line.

    Figure 15-6: Diag Line on Plot

    This shows a line connecting the two clicked points and its slope, with both X and Y axis intercepts, as shown in figure 15-6.

Set Variables

When a rescale rectangle is shown on a plot, its X and Y values can be copied to system variables. There are four reserved variables for this purpose: X_LOW, X_HIGH, Y_LOW, and Y_HIGH. This is useful in setting X and Y limits for optimization by specifying these variables in the Optimizer Options Table.

  1. To perform Set Variables, define these system variables at any level. Only the variables of interest must be defined.
  2. Place a rescale rectangle on a plot as described in the Rescale the Plot section.
  3. Press LEFT on the window title to get the pulldown menu, and release on Set Variables.

    NOTE: The data values are taken directly from the plot. Therefore it may be necessary to transform those values to another form when they are used in the Optimizer Options Table. For example, if the optimization target is log(ic) and the plot shows ic versus ve with LOG10 Y axis type, the Y Bound in Optimization should be log(Y_LOW) and log(Y_HIGH).

Dump to a Printer

The procedure for dumping a Plot to a printer is as follow s:

NOTE: To give a white background to a graphics dump regardless of the current background color in a plot, define the DUMP_WHITE system variable as Yes. Otherwise, the printer output gets the same background color used in the plot.

  1. press LEFT on the window title to get the pulldown menu and release on Dump To Plotter. This pops up a dialog box in which you enter an HP-UX command as shown in figure 15-8. The command in this dialog gets input through its stdin from IC-CAP. This input data has a Starbase format on HP and XWD format on Sun.

    Figure 15-8: Printer Dialog

  2. Click LEFT on the OK button of the dialog box. This generates a series of PCL commands which draw the graph, and pass the commands to the printer spoo1er lp.

    NOTE: You must have a printer spooler rnnning to use the example print command above. Refer to the HP-UX command lp for more information on spooling.

  3. This example assumes the use of a monochrome printer. To use a co1or printer such as HP PaintJet, assign 180 to the system variable DUMP_DPI and use the following command in the Printer Dialog Box for a spooled color printer named pjet: 
       pcltrans -e3 -C -r180 | lp -oraw -dpjet
  4. To change the dot resolution for a finer output, follow the table below. Note that a finer output requires more memory and processing time. Refer to the HP-UX command pcltrans for more information on its options about dot expansion and color handling. 
    Quality     Options        LaserJet       PaintJet

Normal      DUMP_DPI       300            180
            pcltrans       -e3            -e3 -C -r180

Fine        DUMP_DPI       450            270
            pcltrans       -e2            -e2 -C -r270

    Table 15-4: Printer Dot Resolution and Options

    NOTE: The plotter and printer may exist on the same HP-IB with the measurement instruments. However, do not use the instruments while plotting or printing a graph. The better way is to use a separate HP-IB card dedicated for use by instruments only. Refer to chapter 11 Measurement for more information about the HP-IB.

    NOTE: The printer command entered in the above dialog is executed as a background process through /bin/sh. Thus the control returns to IC-CAP as soon as this child process is spawned.

    NOTE: It is necessary to have at least 1MB RAM on a PCL printer to hold either A4 or Letter size data. The HP LaserJet IIP initially comes with only 512KB RAM which is not enough for this size. To have a smaller dump for this memory size, change the pcltrans argument as follows: 

       pcltrans -el | lp -oraw -dljet
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