   --- Graphitude Help ---

This is Graphitude -- an easy-to-use scientific calculator & plotting program.

Graphitude is (c) Copyright 2001, P. Lutus.

Graphitude is CareWare (no money, nor or ever). Please read about CareWare at www.arachnoid.com/careware.

   --- Introduction ---

* For a menu of commands and demos, press the right mouse button if your system has one (or, if not, press the "Menu" button at the lower right).

* Be sure to click the demo examples to see what Graphitude can do.

* To get this help file back on display, choose "Help" in the menu.

* Calculator mode. In the "Enter:" window, type "sqrt(2)" and press Enter. See the result in the "Results:"  window.

* To make a graph, you need to type in an equation in the "Enter:" window, like this:

y = sin(4x)

Then press the "x-y" button to see your graph. Press "Rescale" to automatically scale your graph.

* Use the "x vars" window to define the variables used on the horizontal axis.

* Use the "y vars" window to define one or more variables used on the vertical axis.

Example -- type:

a = sin(4x);b = sin(7x);c = sin(9x)

Then enter "x" in the "x vars" window if this is not already true, and "a,b,c" in the "Y vars" window. Press  "X-Y." Notice that three graphs are drawn.

* Complicated equations can be entered in parts. Keeping the above entries, enter:

y = a b c

(Note the implied multiply. If two operands are separated by a space, multiplication is assumed). Change "x vars" to "x" and "Y vars" to "y" (these are case-sensitive) if they aren't already. Press "x-y." The new graph is equivalent to y = sin(x*4) * sin(x*7) * sin(x*9). Do you see why?

* Polar graphs - use "Polar" to show them. Enter:

x=sin(t) t/20;y = cos(t) t/20

Change "x vars" to "x", "y vars" to "y" if they aren't already, enter "0" for "t min" and "30" for "t max". Press "polar," then "Rescale."

* Multiple polar graphs -- enter "x,y" for "x vars" and "y,x" for "y vars." Press "Rescale." Do you see why this worked? The first polar graph used the x (for horizontal) and y (vertical) definitions, the second one simply reversed them.

* Graph Positions

To get x,y positions in the graph, point and click the mouse in the graph. The cursor position will appear in the results window.

* Application Vs. Applet

When Graphitude is running as an applet (in a Web page), it doesn't have full features (no copy & paste or file load or save). These features can be gotten by running Graphitude independently.

If you choose menu option "Relaunch in Resizable Window" from a Web page, this will let you resize the graph, but you still won't be able to copy or save. To get this ability, simply download the application from the Home Page at www.arachnoid.com/graphitude and install it on your machine.

* Editing/removing symbols from the symbol table.

To remove a symbol (a variable definition or an equation), in the Enter window simply type (symbol)= and press Enter. This erases it.

To get a symbol from the symbol table into the editing window, type (symbol)?.

For larger editing tasks, use copy & paste (see "Application Vs. Applet" above) or file load and save -- any text editor can create data for Graphitude, or receive data from Graphitude.

* Available functions - choose the menu + "List Functions" to see the list.

* Clipboard functions on Edit ... Copy Text & Paste Symbols -- you can copy & paste symbol definitions to/from the clipboard (see "Application Vs. Applet" above).

You can even select and copy the examples from this help file, and choose "Edit...Paste" to enter them into the symbol table (no matter what is on display). This requires that Graphitude be running as an application.

* File ... Load symbols, Save symbols and Save Graph. Available when Graphitude is run as an application. You can edit a symbol file externally and load it as a file, or you can copy & paste it.

* Reserved Variable Names

Graphitude uses some variable names to allow a full setup to be loaded from a file. To see their names, choose menu option "List Functions." The reserved names appear at the bottom of this list.

The variables can be entered into the symbol table, and when they do, they override the individual window entries. So remember -- if you enter a new value in a window and it has no effect, look for an overriding defined variable.

* Recursion

Graphitude's expression processor works like the computer language Lisp -- it is recursive. If you type a definition in terms of another definition, and that definition is defined in terms of something else, all this will be sorted out by the processor.

But there is one thing you need to know about recursive processing -- if two symbols are defined in terms of each other, this creates a circular reference and the computation cannot be carried out.

To see an example, enter this:

a = b;b = c;c = d;d = a;a

This message will appear in the results window:

"Error: Circular Reference"

* Size

To create a larger graph, before saving it, increase the size of the application.

* Comments

You can enter comments into the symbol table like this:

z = sqrt(x^2+y^2)  // magnitude

The comments will be preserved if you save or copy the file.

* Multiple statements

To save time and effort, you can enter multiple statements in the Enter window. Just separate them with semicolons: ";". The parser will place each symbol on a separate line in the symbol table.

* Symbolic Entries

You can enter symbolic entries in the graph constant windows. For example, you might want the X graph range to be -2 PI to 2 PI. Enter it just that way.

The Graphitude Home Page is www.arachnoid.com/graphitude

Graphitude is CareWare. Read about CareWare at www.arachnoid.com/careware.
