DPGraph Quick Start



This document is meant to give you a short introduction to the downloading and use of David Parker’s graphing utility, DPGraph.  To learn more about DPGraph, please read the help file.


To download DPGraph:


1)    Go to http://dpgraph.com and click on List of Site Subscribers link in the yellow box at the top of the page. 

2)    Then scroll down until you find the link for University of Illinois, Urbana-Champaign, 61801/20, US. 

3)    Click on the link and then click “save” when the dialog box comes up. 

4)    Then double click on the installation file to install. 

5)    Once you have it installed, just click on the DPGraph icon on your desktop and the program will begin.


Entering expressions:


According to David Parker, the seven most common mistakes when creating graphs in the EDIT dialog box are: 


1)    Leaving out asterisks for multiplication

2)    Leaving out equals signs or inequality signs

3)    Leaving out the parentheses for lists

4)    Trying to use equalities in intersections

5)    Putting a space inside the two-character symbols: =, >=, or <=

6)    Using the parametric variables u or v in implicit graphs

7)    Using the implicit variables x, y, z, r, theta, rho, or phi in parametric graphs.


The commands in DPGraph files can extend over more than one line.  There must be an opening parenthesis on the first line of the command, and a closing parenthesis on the last line.  For example, the command:


    GRAPH3D( (X^2+Y^2+Z^2=9,SIN(X)+SIN(Y)=SIN(Z)) )

can also be written as:

    GRAPH3D( (X^2+Y^2+Z^2=9,

              SIN(X)+SIN(Y)=SIN(Z)) )


The GRAPH3D command must be the last command.


With experience you may find the following technique useful when exploring a new surface.  OPEN the file DEFAULTS.DPG, go to EDIT, modify the default equation, and then EXECUTE.  You can refer to the following lists when inputting or editing the equations:



pi       (pi)

e        (base of natural logarithms)



x        (x variable for implicit graphing)

y       (y variable for implicit graphing)

z        (z variable for implicit graphing)

r        (polar radius, r=sqrt(x^2+y^2))

theta   (polar angle, 0<=theta<2*pi, theta=angle(-x,-y)+pi)

rho     (spherical radius, rho=sqrt(x^2+y^2+z^2))

phi     (spherical angle, 0<=phi<=pi, phi=angle(z,r))

u        (u variable for parametric graphs)

v        (v variable for parametric graphs)

a        (a variable for scrollbar)

b        (b variable for scrollbar)

c        (c variable for scrollbar)

d        (d variable for scrollbar)

time    (current time for graphs that change with time)



=       (equals, for entering equations)

+       (addition or leading plus sign)

-        (subtraction or leading minus sign)

*        (multiplication)

/        (division)

^        (powers)



cos     (cosine)

ln       (log base e)

log      (log base 10)

sin      (sine)

sqrt    (square root)

tan     (tangent)

angle   (-pi <= angle of (x,y) from positive x axis <= pi)

cylindrical      (parametric graph in cylindrical coordinates)

rectangular     (parametric graph in rectangular coordinates)

spherical       (parametric graph in spherical coordinates)


(For more symbols and functions, see the help file.)


Saving your files:


DPGraph files have a file type of .DPG.  There are two kinds of DPG files: binary and ASCII.  DPGraph can read and write either type of DPG file, but the DPGraph Viewer can only read binary DPG files.


Binary DPG files are compressed and contain error detection information for more reliable transmission.  ASCII DPG files are readable and editable by Notepad and many other text editors. 


For more options, including those that will improve the appearance of your graph, please refer to the online help file.