<program> <version>: Help

This is <program> <version>, Copyright (c) 2009, P. Lutus.

<program> is released under the GPL:

http://www.gnu.org/licenses/gpl.html

To learn more about <program> and to get the latest version, visit:

http://www.arachnoid.com/<program>

*** Calculator

The <program> calculator uses RPN (Reverse Polish Notation), an architecture made famous by Hewlett-Packard (there is no connection between <program> and HP). RPN has many advantages over algebraic calculators, but there is a learning curve for the uninitiated.

To multiply 7 by 9 in an algebraic calculator, one might proceed thus:

Press 7
Press *
Press 9
Press =

In RPN, the same operation looks like this:

Press 7
Press Enter
Press 9
Press *

The above example is meant only to show the procedure, not the advantage RPN has over algebraic calculators. For that, we turn to a more complex problem. In this example, we need to divide the result of two additions:

y = (a + b) / (c + d)

In this example, the operations are performed in a counterintuitive order, which would require quite a lot of manipulation in an algebraic calculator. But using RPN, it's easy:

Enter a
Enter b
Enter +
Enter c
Enter d
Enter +
Enter /

You may have noticed that in RPN, mathematical operators always follow the numbers. Another name for RPN is "postfix," meaning the operators always follow the values to be operated on.

*** The Stack

RPN uses something called a "stack" to store pending values -- each time the user enters a new value, it is placed on the stack, and when a mathematical operation is needed, one or two numbers are removed from the stack, an operation is performed, and the result is returned to the stack. In <program>, the four most recent stack values are always visible to help the user keep track of complex operations, but the stack used in <program> is not limited to four values -- there is essentially no limit to the number of pending operations.

*** Making Entries

Unlike a hand-held calculator, <program> doesn't require the user to press buttons unnecessarily. The "Entry" window will accept a string of number and operator entries, all of which are carried out when "Enter" is pressed on the keyboard. Here is an example -- we want to find the hypotenuse of a triangle whose other two sides are 15 and 17 units in length. The equation for this case is:

hypotenuse = sqrt(a^2+b^2)

for a = 15 and b = 17, this is the entry we need to make:

15 sq 17 sq + sqrt (Enter)

Result: 22.67156809750927

NOTE: There are text shortcuts for each of the calculator's buttons -- hover the mouse cursor over a button to see its shortcut.

*** Display Mode and Resolution Settings

To select display mode and resolution, use the controls at the top of the calculator display. The "All" display mode tries to intelligently switch between fixed-point and scientific display based on the magnitude of the displayed number. Use the drop-down list of decimal resolutions to select the desired number of digits to the right of the decimal point.

*** Special Entry Modes

Use the rightmost drop-down list to select entry and display modes:

Display       Explanation
---------------------
"dd.dddd"     Default floating-point display and entry mode.

Use this mode for normal calculator operations.

"hh mm ss"    Hour, minute, second display and entry mode.

In this mode, the user may enter three values: hours, minutes and seconds (or degrees, minutes and seconds), separated by spaces. In this mode the stack display shows both the full decimal representation and the HMS format simultaneously.

"hh mm.mmmm" Hour, decimal minute display and entry mode.

This mode is much like the HMS mode except that the minute value is a floating-point entry. This format is commonly seen in GPS positions.

"ff ii ii/ii"

This mode is for those unfortunate souls who must use the outdated foot-inch-fractional inch notation scheme used in civil engineering in English-speaking countries. Once this mode has been selected, the user can make entries such as:

13 7 7/16 9 5 5/8 + (Enter)

Result: 23.08854166666667 (23 ft. 1 1/16 in.)

Because the calculator expects three components per entry in this mode, the above example is interpreted as two numeric entries followed by an addition operator.

Remember about these special entry modes that numeric inputs obey the selected mode -- if a mode is chosen that displays three components as in the HMS and foot-inch-fraction modes, three components are expected as input, separated by spaces, as in the above example. In some cases, place-holder zeros may be required:

3 7 3/16 0 0 1/2 + (Enter)

Result: 3.640625000000000 (3 ft. 7 11/16 in.)

This is how one adds 1/2 inch to an existing foot-inch-fraction value.

Obviously at some point, the English system will be abandoned in favor of Metric and life will become much simpler for everyone. In the meantime, this entry mode will efficiently accept, compute and display dimensional measurements expressed in the supremely goofy foot-inch-fractional inch scheme.

*** Financial, Statistical and Base Conversion Dialogs

These dialogs, selectable using tabs at the bottom of the display, have their own separate help screens, readable while performing computations. They provide frequently-used financial computations, statistical probability calculations, and number base conversions.

*** Miscellaneous Notes

To review and recover previously typed entries in the Calculator dialog, press the up-arrow and down-arrow keys. This only works for typed commands, not those issued by way of button-presses.

The <program> trigonometric functions use and return arguments in degrees.

*** Bug Reports

To report a bug in <program>, not to ask for help using it, leave a message at:

http://arachnoid.com/messages

Be sure to say which version of <program> you have, which Java version you are using, and what kind of system you have.
