Graph Software for Scientists and Engineers

Frequently asked questions

Most of the questions you might have concerning the functionality of DPlot are answered in the Help file and the online Help manual. In particular, new users will find the "How do I...?" section useful. Those questions that seem to crop up frequently in e-mail inquiries are also addressed here. Have another one? Let us know.

Can I use DPlot to create blank graph paper?
How many data points can I plot?
How do I import my CSV data into DPlot?
How do I import my data files that use a non-supported format into DPlot?
There is no DPlot menu in Excel. How do I make the Excel Add-In work?
How do I get started using the Excel Add-In?
On startup Excel now shows Run-time error '438'. What's up with that?
How do I make a graph of a circle?
How do I graph an inequality?
How do I change the direction of coordinate axes?
How do I create a scatter plot?
How do I save a plot to an EPS (Encapsulated PostScript) file?
How do I save a plot to a PDF (Portable Document Format) file?
How do I call DPlot from my Visual Basic program?
How do I import a plot into PowerPoint?
How do I batch print a large number of files?
How do I create a series of plots with the same settings (scaling, labels, colors, etc.)?
How do I force DPlot to create a triangular mesh of my 3D points that is not convex?
How do I create a waterfall plot?
Where can I get free stock market data suitable for plotting in DPlot?
As a software developer, can I distribute DPlot with my application?
Help! DPlot's Help doesn't work!
I've bought the licensed version. Why is the watermark still shown on DPlot graphs?
Why don't you answer my e-mail?
What is our privacy policy?
 


Can I use DPlot to create blank graph paper?

Certainly! Though DPlot will only draw a graph for which there is data (one or more data points), you can easily hide that data by setting the line and symbol styles to "None". Follow these steps to create publication-quality blank graph paper. We'll create a macro to automate this process so that you can quickly recreate the same blank paper at a later date. The example shown here is for log-log graph paper, but you can easily adapt the macro to other scale types or other parameters for this same scaling.

Select the Macro command on the File menu. Enter a name for the macro that you're about to create that you'll remember next week. In the example below we'll be creating log-log graph paper with 3 cycles on the X axis, 4 on the Y, so name the macro "loglog3x4". Now click the "Edit/Create" button.

Select the text below with your mouse, right-click and select Copy. In the Macro Editor, click the Paste button. If you want to assign a shortcut key to the macro, select one of the key combinations in the "Shortcut" list. Now click the "Save" button to save the macro. To now run the macro and create your graph paper, if you used a shortcut key you can simply press that key combination. Otherwise, select the Macro command from the File menu, select your macro from the list, and click "Run"

FileNew()                ' Create a blank XY plot
XYXY(2,1,1,1000,10000)   ' Adds 2 points
Scale(4)                 ' Log X - Log Y
HideCurve(1)             ' Don't draw the "curve"
Size(1,6,8,1)            ' Size of the graph - 6" wide, 8" tall
NumberFormat(0,12)       ' 12="none" for number format
NumberFormat(1,12)       ' This means numbers won't be drawn on the axes
LineWidth(-1,20)         ' Pen for axes is 0.02 inches
LineWidth(0,10)          ' Pen for major grid lines is 0.01 inches
LineWidth(-3,5)          ' Pen for minor grid lines is 0.005 inches
GridLines(1)             ' Box around plot w/ grid lines
DenseGridLines(1)        ' Looks crowded on the display, but nice when printed
Color(0,128,128,128)     ' Set grid color to a med. gray

Click here for a PDF file of this graph paper.

For help on any macro commands, simply move the text insertion point to the appropriate line and click the Help button in the macro editor. Each of the commands shown above is explained in detail in the Help file.

For additional graph paper examples, including free PDF downloads of those examples, see the Graph Paper page.

How many data points can I plot?

We frequently work with plots containing several curves and 2 million or more points per curve. The actual limit is determined by the largest continuous block of free memory (generally less than 2Gb minus the overhead of DPlot's code+resources and any DLLs that have been loaded). On most systems (with sufficient RAM and/or virtual memory) you will be limited to about 70-90 million points.
 

How do I import my CSV (comma-separated values) data into DPlot?

If your files are XY data with X values in the first column and all subsequent columns being Y values for separate curves, you can drag-and-drop your CSV files onto DPlot and it will correctly interpret them, including (if present) titles and axis labels (for a single curve) or legend entries for multiple curves. CSV files may also be opened with the File>Open menu command, of course (select the Multiple columns file type). DPlot includes support for 3D (X,Y,Z) data and for XY data also allows you to specify which columns to plot, which column is X, or to specify that the data is alternating X,Y columns rather than X,Y,Y,Y. "CSV" is actually a bit misleading in this case, as DPlot will also allow tab- or space-separated columns. DPlot will also allow you to save your data to a CSV file that can be read directly by Microsoft Excel.
 

How do I import my data files that use a non-supported format into DPlot?

With a file import plugin. You can add plugin modules (DLL's) to import data into DPlot (export, too). Example C source code for a file import plugin is provided in the plugins download. This is a separate download not included with the main distribution. Alternatively, if you're unaccustomed to writing DLL's we'd be happy to produce a plugin for licensed users at no charge, provided that you can furnish the file format details. Contact us for more information.

In many cases DPlot may not have direct support for a specific format, but you may be able to easily convert that format to a form that DPlot does handle. For example, Hobo data loggers from Onset Computer Corporation produce a proprietary format for which Onset provides no documentation. But the software products BoxCar and LogUtil from Onset can be used to save the file in a format that DPlot will read correctly. The LogUtil program is free and can be downloaded from the Onset Software Utilities page. Using LogUtil, export your Hobo data logger file to its "Custom" format with "Month/Day/Year Hours:Minutes:Seconds". The resulting file may be opened in DPlot by drag-and-dropping it onto the DPlot window or with the File Open menu command as a "Multiple columns" file.
 

There is no DPlot menu in Excel. How do I make the Excel Add-In work?

If you did not elect to install the optional Add-In when you ran the DPlot setup program, you will need to re-run the setup program and make sure to check the "MS Excel Add-In" box on the "Select Components" screen. If you did elect to install the Add-In, the problem is most likely that the security settings in Excel prevented the Add-In installation from being completed. In that case open Excel.

On Excel 2003 and previous versions
On the Tools menu select Add-Ins:

Excel Tools menu

There should be a "DPlot Interface" box:

Excel Add-Ins

Check that box, then click OK. If there is not a "DPlot Interface" box, then most likely DPlot was installed by a different user than you, probably an administrator because you have a limited-privileges user account. In that case click the "Browse" button and navigate to the folder where DPlot was installed (default location=c:\Program Files\DPlot or c:\Program Files (x86)\DPlot on 64-bit versions of Windows). Select the file dplotlib.xla then click OK.

 

On Excel 2007
Click the Office button in the upper left corner:

Excel 2007 Office button

On the resulting screen click "Excel Options" at the bottom of the window.

Click "Add-Ins" in the left pane.

At the bottom of the next screen, ensure that the "Manage" selection is "Excel Add-Ins", then click "Go"

The next dialog is identical to that for Excel 2003 shown above. Check the "DPlot Interface" box (or follow the instructions above if that box is not present), then click OK.

On Excel 2010 and later
Click the File tab at the left end of the ribbon.

On the resulting screen click "Options" at the bottom of the left pane.

Click "Add-Ins" in the left pane.

At the bottom of the next screen, ensure that the "Manage" selection is "Excel Add-Ins", then click "Go"

The next dialog is identical to that for previous versions shown above. Check the "DPlot Interface" box (or follow the instructions above if that box is not present), then click OK.
 

How do I get started using the Excel Add-In?

To use the Add-In, start Microsoft Excel and open the workbook containing the data you'd like to plot in DPlot. If you are unfamiliar with the Add-In you will find the example Excel workbook EXAMPLES.XLS useful. This workbook includes examples for all of the functions in the Add-In. EXAMPLES.XLS is installed to the DPlot folder (if you used the default installation options that will be c:\Program Files\DPlot or c:\Program Files (x86)\DPlot on 64-bit versions of Windows).

If you are reasonably comfortable with Excel's VBA (Visual Basic for Applications) and would like to modify the Add-In (for example to permanently change one or more graph formatting options), search DPlot's Help file for "Add-In". At the bottom of the "Using the DPlot Interface Add-In for Microsoft Excel" topic, see "Editing the Add-in".
 

On startup Excel now shows Run-time error '438'. What's up with that?

Most likely you've at some point performed an operation that has made Excel's toolbar temporarily lose its mind. To correct this situation:

  • Start Excel. On the Tools menu select Customize.
  • On the resulting Customize dialog click the Toolbars tab.
  • Near the end of the Toolbars list, find Worksheet Menu Bar. Select that entry so that it is highlighted.
  • Click the Reset button. When asked whether you really want to do this, click OK.
  • Click the Close button, then exit and restart Excel.
  • If you previously deactivated the DPlot Add-In to get rid of this error message, select Tools>Addins, check the DPlot Interface box, then click OK.

How do I make a graph of a circle?

The Y=f(X) command will only generate data points for which there is one unique Y value for every X. So even though Y=sqrt(R^2-X^2) is the correct equation for a circle, use of this equation with Y=f(X) will only result in a semicircle (the positive Y half). But don't despair; generating a circle is no problem with X=f(T), Y=g(T). With T varying from 0 to 360 degrees, X=R*cos(T), Y=R*sin(T) defines a circle of radius R (substitute the actual radius for "R") centered at the origin. Of course if you want a circle centered at (H,K), you'd use X=H+R*cos(T) and Y=K+R*sin(T).

Initially the physical dimensions of your circle will most likely not be circular, depending on the window size. That's simply because by default, DPlot uses as much of the display monitor as possible to plot your data. You can force circular circles by using the Extents/Intervals/Size command and specifying equal extents for the X and Y axes and equal physical dimensions (check Specify plot size and enter equal values for the plot width and height).

The X=f(T), Y=g(T) command is of course useful for other geometric shapes that have more than one Y value for each X. To plot an ellipse X^2/A^2 + Y^2/B^2 = 1, for example, use X=A*cos(T), Y=B*sin(T) with, again, T varying from 0 to 360 degrees.
 

How do I graph an inequality?

Rather than a line or a curve, the solution set for an inequality involving X and Y fills an area on the XY plane. An equation defines the boundary or edge of the set. Although DPlot will not directly solve for and plot inequalities, you can easily do so yourself in a few steps. First rearrange the inequality (if necessary) in the form Y < (or <, >, >) f(X). Use the Y=f(X) command on the Generate menu to plot the boundary of the inequality. Then use the Fill Between Curves command on the Options menu to fill in the area above or below the boundary, depending on whether the inequality is > (above the boundary) or < (below the boundary). For example, here is the solution to y > 2x-5.

Graphing inequalities example

For detailed instructions on how this graph was created and for more information on graphing inequalities, see the Graphing Inequalities page.

How do I change the direction of coordinate axes?

Normally, values on a linear or logarithmic scale increase from left to right (or bottom to top). You can change the direction by selecting the Extents/Intervals/Size command on the Options menu and checking the appropriate "Invert" checkbox below "Specify Extents". For example, if your logarithmic scale on the X axis normally extends from 1 on the left to 1000 on the right, check "Invert X" to change the extents to 1000 on the left, 1 on the right.

For 3D data you can achieve similar results by specifying negative scale factors for the appropriate axes with the Contour Options (for surface plots) or Scatter Plot Options (for 3D scatter plots) commands under the Options menu.
 

How do I create a scatter plot?

In this context, by "scatter plot" we mean a plot with symbols at each data point, and no line segments connecting the data points. Right-click on a curve, select Symbol style, then click on the symbol style you want:

symbol types

Right-click again on the curve, select Line style, then select "None".

line styles

Repeat for each curve. If you have more than one or two curves, you might prefer to select the Symbol/Line Styles command on the Options menu. For all curves, choose "0 - none" for the line type, and select the symbol type you want to use for each curve. The Symbol/Line Styles dialog is also used to set the size and frequency of symbols.

How do I save a plot to an EPS (Encapsulated PostScript) file?

DPlot has no direct support for EPS output. But Windows does, and it's fairly simple to make DPlot produce EPS files. If you do not already have a PostScript printer installed:

  • Start Control Panel.
  • Select Printers, then Add a Printer.
  • Click Next to cycle through the first couple of dialogs. You're now going to install a PostScript printer. It doesn't matter if you actually have a particular printer or not since you won't be printing to it. If you know you'll only want to save B&W output, any of the HP LaserJet PostScript printers are good choices. If you want color information saved to the file, of course select a color printer, e.g. the HP Color LaserJet 5/5M. Of course if you know what the final output destination for your EPS files is and that printer driver is available, then you should install that printer.
  • After selecting a printer click Next. Under Available ports select FILE:. This is not critical since the Print dialog in DPlot will give you the option of printing to a file, but it might save you a few headaches of attempting to print to a nonexistant printer later on.
  • Click Next to cycle through the remaining dialogs, and... you're done.

After selecting the Print command in DPlot, be sure to select the PostScript printer from the list of available printers. Click Properties, then... well then what you do will be largely dependent on what version of Windows you're running and which printer driver you're using. For the HP LaserJet family of printers on Windows XP:

  1. Click the "Advanced" button.
  2. Under Document Options>PostScript Options set PostScript Output Option to "Encapsulated PostScript (EPS)".
  3. To ensure compatibility with the widest variety of applications, set PostScript Language Level to 1, rather than the default 2. (Microsoft Word, for example, will open but will not display an EPS file using level 2, but displays level 1 files just fine.)
  4. Click OK twice to return to the main Print dialog.
HP Advanced Options dialog

Back on the main Print dialog, be sure to check Print to file. You'll be presented with a Print to File dialog that will allow you to specify the name of the output file. Don't worry if the default filename extension is ".prn"; just type the filename with an extension of ".eps".
 

How do I save a plot to a PDF (Portable Document Format) file?

As with EPS files, DPlot does not directly support output of the PDF format and the solution is very similar to the EPS problem. However, Windows isn't much help here and you'll need Adobe® Acrobat or any other Adobe product that includes Acrobat Distiller or the Adobe PDF virtual printer driver. If you have Acrobat installed you should see Acrobat Distiller and/or Adobe PDF as one of the possible choices of printer in DPlot's Print dialog. Select it. You may also have an option of Acrobat PDFWriter. However, PDFWriter has problems with DPlot contour plots, while Distiller and Adobe PDF handle these plots perfectly.

Note: The Adobe printer drivers offer several methods for compressing bitmap images, with JPEG compression being the default. The JPEG method does compress the image very effectively, but the result is generally poor with DPlot-produced graphics. ZIP compression produces larger files but much better quality images.

If you do not have access to one of those Adobe® products, there are several low-cost PDF virtual printer drivers available on the internet. The following vendors provide free trial versions of low-cost PDF printer drivers that have all been tested successfully with DPlot:

This example PDF file was created with Pdf995. Similar results are achieved with each of the products listed above.

How do I call DPlot from my Visual Basic program?

By far the easiest way is to link your program with DPLOTLIB.DLL. This developer's tool is included with the DPlot Jr as well as the full DPlot distributions and also as a separate download. DPLOTLIB works with either the full version of DPlot or DPlot Jr (it will always choose the full version if both are installed). Example programs with full Visual Basic (C and FORTRAN, too) source code are included. Documentation is included with the distribution and is also available online.

VB users please note: You do not need to add a reference to DPLOTLIB.DLL in your VB project. That VB feature only works with COM modules, which DPLOTLIB.DLL is not, and attempting to add a reference will only result in an error from VB. If you follow the example programs you should not have a problem, but if you do, let us know.
 

How do I import a plot into PowerPoint?

Or, for that matter, any of the Microsoft Office products? Very easily. Use the Copy command (or corresponding toolbar button or shortcut key) to copy your plot to the clipboard, then paste into the target program. For XY plots DPlot creates both metafile and bitmap representations of your plot; 3D plots are copied as bitmaps only. In general, metafiles are more flexible than bitmaps since they are scaleable. If you want a bitmap rather than a metafile, use the target application's Paste Special command rather than Paste, and select Device independent bitmap. DPlot also allows you to specify the size of the metafile and/or bitmap prior to copying to the clipboard, so you can make the plot exactly the size you want within DPlot without worrying about scaling the picture in the other application.
 

How do I batch print a large number of files?

With a DPlot macro (created within DPlot). The following macro will print all of the CSV files in the folder C:\MYDATA.

Directory("C:\MYDATA")
FileType(4)
ForFilesIn("*.CSV")
  FilePrint()
  FileClose()
NextFile

Macros are of course good for other batch operations as well. The following macro reads all CSV files in the folder C:\MYDATA and saves Windows metafiles with default dimensions of 6x4 inches and with the same filename and a ".wmf" extension.

Directory("C:\MYDATA")
FileType(4)
SetMetafileDims(6,4)
ForFilesIn("*.CSV")
  FileSaveAs(4096,"")
  FileClose()
NextFile

 

How do I create a series of plots with the same settings (scaling, labels, colors, etc.)?

There are a number of ways to accomplish this. Which method is best for you will depend on the frequency with which you use these same settings.

  1. Create the first plot with all of the formatting that you want to use in subsequent plots. Select Save Preferences on the File menu. After creating any subsequent plots, whether by DDE, reading a file, pasting from the Clipboard, or entering values using Edit Data, use Get Preferences on the File menu to restore the previously saved preferences. This includes titles and axis labels (existing labels will not be replaced), colors, line styles, scaling, etc.

    You can easily help automate this last step by creating a macro to open this preferences file and assigning a hotkey to the macro. For example, this macro:

    GetPreferences("myprefs.set")
    ViewRedraw()

    will read the file myprefs.set from the default Preferences folder (%appdata%\DPlot\Preferences on Windows 2000 and later versions) and redraw the plot using the settings found in that file.
     

  2. Same as above, but save your preferences to DEFAULT.SET in the default folder (%appdata%\DPlot\Preferences on Windows 2000 and later, or the folder where dplot.exe is located on Windows 95 and 98). DEFAULT.SET will be processed every time a new plot is created, without reading settings using the Get Preferences command.
     
  3. If you want to restore some, but not all, of the settings saved to a preferences file, e.g. colors only, you can fairly easily create a macro to reproduce all the settings you're interested in. A full description of creating macros and all available macro commands is in DPlot's Help file.

How do I force DPlot to create a triangular mesh of my 3D points that is not convex?

The short answer is... you can't, at least not initially. DPlot is only reading X,Y,Z values from your input source, whether that source is a file, the Windows Clipboard, communication from another program, or the Edit Data command. This is not enough information to determine where the edges of the surface should be, or for that matter to determine whether your surface should have any interior holes. DPlot always creates a convex triangular mesh from X,Y,Z input, which for many applications is exactly what you want. It is of course possible that you will not want a convex mesh. In this case DPlot will have created triangles outside the desired limits of your plot. The solution is to use the Define Boundary menu command to describe the exterior boundary of your surface. See the description of the Define Boundary command for more information.

How do I create a waterfall plot?

Waterfall plots can be created directly from 3D points on a rectangular grid - for example points generated with the Z=f(X,Y) command or sent to DPlot from another application through the DPLOTLIB interface. But in most cases you'll start with random 3D points, for example X,Y,Z columns pasted from the clipboard, and the waterfall plot option will be disabled. To reorganize these points on a rectangular grid, use the Generate Mesh command on the Options menu. This command gives you several options controlling the complexity of the grid and the smoothness of the generated mesh. After running Generate Mesh you'll find that the waterfall plot option is now enabled for 3D plots.
 

Where can I get free stock market data suitable for plotting in DPlot?

This isn't strictly a DPlot question, of course, but if you are interested in the stock market you will probably find this handy.

  1. In your internet browser go to http://finance.yahoo.com.
  2. Enter stock symbol in the text box adjacent to the Search Finance button at the top of the screen, then click the Search Finance button. If you do not know the appropriate symbol, type the name of the company in this box.
  3. When stock data page displays, click on Historical Prices in the left column.
  4. Set the date range you are interested in, then click the Download Data link at the top of the table.
  5. You have a couple of options at this point, dependent on whether you have Microsoft Excel installed or not. If you choose Open, the spreadsheet will be opened in the default application for CSV files (normally Excel). If you choose Save then you can later open this file in either Excel or in DPlot (by drag-and-drop, Explorer's right-click "Open With...", or within DPlot with File>Open and file type D.
  6. If you choose to open the data in Excel, as a minimum select the first column (Date) plus whatever columns you are interested in, then select XYYY on the DPlot menu. Don't have a DPlot menu in Excel? Install the Add-In.
  7. Whether opening the file directly in DPlot or using the Excel Add-In, if you plot Volume along with Open, Close, etc., you will probably find that the volume extents are much larger than the price extents. If you want to display Volume data along with Open, Close, etc. then select Options>Multiple Axes, select Independent Y2, under Curve select "Volume", then select Y2. Alternatively, of course, you can opt not to plot Volume on the same graph. Example:
    Stocks example
    Yahoo Finance Stock Data
You can also use DPlot's OHLC chart command to create an Open-High-Low-Close chart and/or a candlestick chart:
OHLC example
Yahoo Finance Stock Data in an OHLC chart
Candlestick chart example
Yahoo Finance Stock Data in a Candlestick chart

As a software developer, can I distribute DPlot with my application?

In short, no. But don't go away yet, there is a solution. If you haven't already checked out DPlot Jr you'll want to take a look. The price is right: it is free. Any plot that your program can produce with DPlot can also be produced with DPlot Jr. If the limitations of DPlot Jr are unsatisfactory to you, contact us for more information on a developer license (allowing you to redistribute DPlot for one fixed fee and no additional charges) and/or a bulk licensing scheme taking advantage of multi-user price bands with purchases spread out over future years.

Help! DPlot's Help doesn't work!

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 later 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.

I've bought the licensed version. Why is the watermark still shown on DPlot graphs?

If you followed the download and installation instructions you received after your purchase, then most likely you previously installed the trial version, and installed the licensed version to a different location. The default location for both programs is c:\Program Files\DPlot or c:\Program Files (x86)\DPlot on 64-bit versions of Windows. If you think this is a possibility then the surest way to correct the problem is to uninstall all copies of DPlot using Control Panel's Add/Remove Programs applet, then reinstall the licensed version.

Why don't you answer my e-mail?

All e-mail inquiries are answered as soon as possible, generally within an hour if sent during normal business hours through late night US Central Time. If you are not receiving answers to DPlot support questions or you are a licensed user signed up for the DPlot update mailing list and are not receiving update notices, it is almost certainly due to the mail being blocked by your mail server, whether it is erroneously flagged as spam, or being held on the server because support@dplot.com is not on your "whitelist". Free e-mail accounts (e.g. yahoo, hotmail) are especially bad about this, as are selected paid accounts - in particular comcast. This situation is not likely to improve as long as the world is plagued with spam. Best suggestion for support questions: use the DPlot Forums to post your question. If you do not want to post your question publicly you can post a private message after registering on the Forums.
 

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