A: Yes there is, if you are willing to experiment just a bit. Select the Title/Axes command on the Text menu. (This also works with the legend and with point labels and text notations). Click within the text box where you want the square root symbol, then click the α button at the bottom of the dialog box:

Now select the left portion of the square root symbol in the next-to-last row, towards the right:

click the Select button, then OK.

For the horizontal bar, the best you can do is an overbar code. This draws a horizontal line above the character(s) that have this attribute. But there is no button on the Title/Axes (or any other) dialog for the overbar code, so you'll need to type it yourself:

Where this all becomes a trial-and-error process is that the overbar is not specifically designed to line up perfectly with the left end of the square root symbol. With some font sizes and weights it appears to be perfect, but with others... it isn't all that good. And the results will vary by output device. Generally if it looks good on the screen it will look good in saved bitmap images or printed out, but may or may not be aligned properly in metafiles. The alignment will vary with font face (Arial tends to work well), and smaller fonts (12-16 pt) tend to do better than larger fonts. Bold fonts definitely do better. But as mentioned at the outset, you'll have to experiment. Here's a 14-pt bold Arial stab at the problem:

Unfortunately this feature does not work at all with subscripts, superscripts, etc., as the overbar will be at varying heights above the baseline. Perhaps a future release will address this problem with a sqrt formatting code.

For a list of all formatting codes see the online Help topic for the Title/Axes command, or within DPlot click the Help button on the Title/Axes dialog box.

Q: I need to know what mathematical algorithm is used for the moving average calculations.

Normally, a moving average will require that the "end regions" of the graph not be included in the graph of the moving average, since, for example, a centered 11-day moving average can't provide data for the first 5 days and therefore can't be graphed. The same is true of the last 5 days in this example. I believe this problem is inherent in all moving average calculation varieties (though I'm open to being educated).

I bring it up because graphing the end-point regions of a moving average generates quite a bit of controversy in the climate sciences where I work because the end regions normally excluded in a moving average have to be filled in based on some sort of (often unscientific) assumption--even a simple "continue the trend" assumption.

A: For versions 2.2.7.0 and earlier, the output of the Moving Average plugin is an average of the last N points, where N is the interval chosen. This is identical to the Moving Average function of Excel's Analysis ToolPak, with the exception that Excel gives "#N/A" for the first N-1 points, while the DPlot plugin gives the average of i points for i<N.

The new version of the Moving Average plugin includes three forms, two of them new: 1) Prior Moving Average (identical to the only previous option), 2) Central Moving Average (more like what you're talking about, with point i equal to the average of points i-(N-1)/2 through i+(N-1)/2, and 3) Cumulative Moving Average, which is the average of all points up to and including the i'th point.

In addition, the new plugin allows you to include (or not) points at the tails of your data. If Include tails is checked, then as before the i'th point for i<N is the average of the first i points for a Prior Moving Average. Similarly, for a Central Moving Average and i<(N+1)/2 or greater than NP-(N-1)/2 (where NP is the number of points in the input), the output is the average of the sampled input points. If Include tails is not checked, then the output will only include points for which i>N for a Prior Moving Average, or i>(N-1)/2 and i<NP-(N-1)/2 for a Central Moving Average.

The new input dialog for the Moving Average plugin (licensed version only):

Which method is appropriate for your use is dependent on what you are measuring. The Prior Moving Average is a well-established standard but for data that tends to increase or decrease over time, introduces a lag in the output: for a steadily increasing record the output will tend to be equal to the input N/2 measurements ago. The Central Moving Average eliminates this lag but may not be appropriate for your use if the current prediction should not be influenced by future data. The Cumulative Moving Average is mostly useful for data that doesn't increase/decrease monotonically over time and for which early data is significant for the present.

The new plugin is included with the 2.2.7.3 release of DPlot. Licensed users who are not on the update mailing list can get this version by selecting the Check for Updates command on the Help menu.

Example (with Include tails checked in all cases):

When selecting Help>Contents in DPlot if you see a screen like this:

...then you almost certainly have DPlot installed on a network server and are running DPlot from a client system. Although the program will run fine in this configuration, the Help file will not. Unfortunately this is a Windows security "feature" introduced with a security patch for Windows XP, also affecting all Vista versions. If you are certain that you will not be viewing any "untrusted" CHM Help files then the good folks at EC Software have provided a fix. Otherwise, your best bet is to install DPlot to all client machines rather than running from a server.

The particulars of this graph aren't really important in this case. The data consists of two "curves"; the bubble magnitudes come from the second curve. The rainfall rate values (bubble magnitudes) vary from ~2.1 - ~11.7. The user in this case wanted to display the rainfall rates in the legend entry for the plot. It would of course be easy enough to type those values for the legend, but we'd like something a bit more automatic that can be stored in a preferences file and/or set in a macro to get the same results for other data. If the legend entry is set to:

$YMIN(2) - $YMAX(2) inches/hr

...then the result looks something like:

The (2) index references the 2^nd curve (the bubble magnitudes). If the (2) were not included, then the legend would use the minimum and maximum values of the "Runoff" curve.

This is fine, but displays more significant figures than we'd like. Text placeholders can include an equation, and the equation itself can contain other text placeholders. So we can use the MROUND function:

$=(MROUND($YMIN(2),0.1)) - $=(MROUND($YMAX(2),0.1)) inches/hr

... to round off the rainfall rate values to the nearest 0.1, and get:

Questions? Let us know.

Syntax:
OverlayDocument(docnum|,alpha|maskcolor||) or
OverlayDocument("caption"|,alpha|,maskcolor||)

In the first form, docnum is the 1-based document index of the plot you want to draw on top of the currently active plot. This value corresponds to the indices you'll see for open documents on the Window menu.

In the second form, "caption" is the title of that plot, shown in the document title bar. If this form is used then the caption must be delineated with quotation marks, as shown.

The optional alpha parameter controls the transparency of the overlay. alpha=0 is completely transparent (invisible, in other words); alpha=255 is opaque (no transparency).

The maskcolor argument specifies a color (red+green*256+blue*65536, or hex 0x00bbggrr) in the overlay that will not be drawn if alpha is between 0 and 255. This is useful for making opaque portions of the overlay transparent: in particular an opaque legend box or contour line labels with an opaque background. This feature does not work particularly well with anti-aliased lines and/or smoothed screen fonts, since you can only specify a single color. Antialiased lines and fonts are generally less of a problem with printed plots.

If you aren't familiar with DPlot macros, there really isn't all that much to it, so don't be scared off just yet. To create a macro select the Macro command on the File menu. Type a name for the macro that you'll remember next week in the Macro Name box, then click Edit/Create. We'll start with something simple: if you have 2 open documents, document 1 is active and you want to overlay it with document 2, type:

OverlayDocument(2)

in the macro editor window, click the Save button, then the Run button.

Example:

Document 1 is a surface plot of the Vicksburg National Military Park area created from NASA SRTM data:

Document 2 is an XY plot created from a Garmin GPS device during a bike ride through that same park:

With document 1 active, the macro command OverlayDocument(2) results in:

This feature hasn't been added to the normal menu commands in DPlot simply because there are several quirks to work out yet. Namely: transparency may (or may not) work correctly in printed plots, depending on your printer. Multiple axes in the overlay plot are not transferred to the overlaid plot. Other than the data itself, most plot features for the overlay plot are ignored: title lines, axis labels, number formatting, etc. These are all necessary and won't likely change. But the legend for a surface plot is also omitted for (currently) the same reason, and there is no way to show that legend. At least some of these limitations will likely be worked out in a future release.

This feature is not intended for use with 3D views of 3D/4D data at this time, though DPlot will not prevent you from using it on those plot types.

Ductile metals do not have a well defined yield point. The yield strength is typically defined by the "0.2% offset strain". The yield strength at 0.2% offset is determined by finding the intersection of the stress-strain curve with a line parallel to the initial slope of the curve and which intercepts the abscissa at 0.2%.

The question, then, is "Is there an easy way to determine the 0.2% offset strain line, without a calculator handy?" Yes, there is. Shown below is a typical stress-strain curve, in this case for a rolled steel bar.

The first step is to find the slope of the elastic portion of the stress-strain curve. You can do that very easily with the Distance from... command on the Info menu. Ensure that Snap cursor to nearest data point is checked, then drag the mouse from a point near the origin along the initial (hopefully linear) slope:

To avoid retyping (and transcription errors), drag your mouse over the "slope" value, right-click and select "Copy". Now select the Y=f(X) command on the Generate menu. The equation we want is simply (in this case) "21.6569856057*(x-2000)" (2000 microinches/inch = 0.2% strain). For the from X value use 2000 (or any smaller value); for to X use a strain value large enough that the line will be certain to cross the stress-strain curve. You can then zoom in if you overshoot the curve by a lot. The with interval dX entry isn't critical, since you'll be generating a straight line.

Finally, select Find Intersections... on the Info menu. (If this command is disabled you likely need to sort the data points with the Sort command on the Edit menu.) Check the Insert data points... and Add labels at intersections boxes, and you get:

... indicating a yield stress of ~70.5ksi at a strain of ~0.005.

Q: Will DPLOT compute the area and or acreage within a closed plotted polygon?

A: Yes. If you use the $AREA shortcut in any text entry (title lines, axis labels, legend, etc.) DPlot will report the area enclosed by your polygon. If the points are arranged in a clockwise direction the value will be positive; if counterclockwise the value will be negative. You can force a positive answer by using the absolute value operation, as in "Area=$=(ABS($AREA))". The initial "$=" tells DPlot an equation follows, which must be enclosed by parentheses.

If you have more than 1 curve then you'll need to use $AREA(n), where n is the 1-based index of the curve.

For most applications (and in particular since you asked about acreage) the value replacing $AREA is perfect. If you're trying to find the area enclosed by what should be a smooth curve, though, you might need to generate more points, if possible. The circle below was generated with X=f(t), Y=g(t) with X=2*cos(t), Y=2*sin(t) with the spacing in t set to 1 degree. The difference between the calculated area and the well-known area of a circle is due to the spacing between points.

In case anybody is wondering, the plain text for that text note is:

R	=2
Area	=$AREA
{\sp}r{\u2}	=$=(PI*4)

with the tab stop set to 5 characters.

For more information see How do I find the area under a curve? in the online manual.

Q: 1. Can DPlot find the area between two curves? Area under a curve?

A:No and yes, mostly. You can embed the area under a curve in any text entry (title line, axis label, legend, etc.) with $AREA(n), where n is the index of the curve.

Since you can embed equations in those same entries and also embed text shortcuts like $AREA in equations, you can indirectly report the area between two curves with something like "$=($AREA(1)-$AREA(2))". This will work fine as long as the curves don't cross. If they DO cross then you can get the area with a bit of manipulation: Use Generate>Y=f(X,Y1,Y2,...) with Y=abs(Y1-Y2) (to find the area between curves 1 and 2), then $AREA() on that new curve to find your answer.

A: Good question :-). Both of those programs will do a few things DPlot will not. Whether that difference is worth 10+ times the price is something users will have to answer for themselves.