
Calculator Help

                                            version: 1.0fc1
                                            created: 08/06/1999 {05:55:36 PM}
                                        last update: 06/10/2005 {05:40:01 PM}


	  	Abstract

Alpha has its own <<calculator>>.  This is a sophisticated RPN stack
calculator, which works on both signed and unsigned decimals, hex integers,
and floating point.  (You might wonder, "# What does 'RPN' mean?"  ...)

It can also serve as an "# Equation Editor".

This "Calculator Example" hyperlink will return the result of typing  

	1<Space>1<Space>+4.2*

or

	1
	Space
	1
	Space
	+
	4.2
	*

It first calculates adds "1, 1" to the stack, adds them, and then calculates
(1 + 1) * 4.2 .


	  	Table Of Contents

"# Basic Usage, RPN modes"
"# More Keyboard Shortcuts"
"# The Calculator Window"
"# Calculator Modes"
"# Equation Editor"
"# 'International' Users"
"# What does 'RPN' mean?"

"# License And Disclaimer"

<<floatNamedMarks>>


	  	Basic Usage, RPN modes

The first four Calculator "modes" use the RPN stack method:

	Signed Decimal
	Unsigned Decimal
	Unsigned Hexadecimal
	Floating Point

* Open the <<calculator>> by selecting "Utils > Calculator".
* The default mode is "Floating Point".
* The cursor is waiting in the User Input field.
* Enter some value, and press Space, Enter, or Return to add it to the stack.
* Enter a new value, and then an operator key (such as +, - *, / ...)

As you perform additional operations, they are recorded in the History
section at the bottom of the window, and the User Input field is cleared for
the next entry.  Click on the 'Clear' hyperlinks to reset the current Value,
Input, or to remove all history items.

As you perform operations, any value in the Current Input field is used as
the primary operator value.  For example, enter "123" and select the menu
item "Calculator > Other Math Functions > sqrt" and you will get

	sqrt(123.0)      11.09053651

If the operation requires two values, then the Current Input and the last
item in the stack will be used.  For example, if your Calculator looks like

	Stack :         ÇClearÈ

	44
	_______________________

	Input :         ÇClearÈ

	123
	_______________________

	History :       ÇClearÈ

	Pushed Stack :   44.0

and you press "/" (for divide) then you will get

	Stack :         ÇClearÈ

	0.3577235772
	_______________________

	Input :         ÇClearÈ


	_______________________

	History :       ÇClearÈ

	Pushed Stack :   44.0
	44.0 / 123.0     0.3577235772

If, however, the Input field is empty when you perform a "binary" operation
requiring two value, then the last two values in the stack will be used.  For
example, if the stack contains

	Stack :         ÇClearÈ

	22
	44
	87
	_______________________


then pressing "/" (with the Input field empty) will produce this:

	Stack :         ÇClearÈ

	22
	0.5057471264
	_______________________

	Input :         ÇClearÈ


	_______________________

	History :       ÇClearÈ

	Pushed Stack :   22.0
	Pushed Stack :   44.0
	Pushed Stack :   87.0
	44.0 / 87.0      0.5057471264

If you have never used an RPN stack calculator before, this might seem a bit
inintuitive at first, but this method is really very flexible.  For example,
if you wanted to calculate

	(4 + 5) * (78 - 6)

you would use these keystrokes:

	4
	Space (or Enter or Return)
	5
	+
	78
	Space
	6
	-
	*

In this case, your final Calculator History section would look like

	History :       ÇClearÈ

	Pushed Stack :   4.0
	4.0 + 5.0        9
	Pushed Stack :   78.0
	78.0 - 6.0       72
	9.0 * 72.0       648

If you want to remove the last item in the stack, move the cursor to the
start of the Input field and press Delete.

If this still seems confusing, you might rather use the "# Equation Editor"
mode for the Calculator as described below.

These are some of the basic operations, where "y" indicates the current
value, and "x" indicates the entry in the User Input field.

	+,-,*,/,|,&,%   Calculates "<Value> <Operation> <Input>"
	~               bitwise NOT
	^               y to the power of x
	<               x << y
	>               x >> y
	n               change y's sign

Additional utility items include

	q               Place the current "y" value in the User Input field.
	i               Swap x and y, i.e. the current value and input fields.
	Space/Enter     Enter the current input value.    

	m               Switch amongst signed/unsigned/hex/floating-point modes.
	x               Show the current mode in the status bar.
	h or ?          Open this window.


	  	More Keyboard Shortcuts

The Calculator menu includes a number of operations with their own special
Keyboard Shortcuts.  Whenever you attempt to call one of these menu commands
or type something outside of the User Input field, the cursor will be
returned to the input line without performing any further operation.


	  	The Calculator Window

When you move or re-size the Calculator window, the current geometry (i.e.
the left, top, right, bottom boundaries) are saved and used the next time
that the Calculator window is created.  There are no preferences to set here,
this is done automatically.

There are, however, some preferences that you can adjust

	Include History Section

If turned on, every operation will be recorded in a History section at the
bottom of the Calculator window.  Click the <Clear> hyperlink to reset it.

	Include Function Hyperlinks

If turned on, most of the Calculator menu items will be displayed in the
window with hyperlinks.  Clicking on them will execute the menu item (in RPN
modes) or insert the function text (in "# Equation Editor" mode.)

	Include Keypad Hyperlinks

This is a Very Clever feature that has little utility, unless you are
addicted to the mouse and never want to use your keyboard or keypad to enter
numerical values or the common "+ - * /" binary function operators.

You can also change the default Font and Font-size used for the window.


	  	Calculator Modes

The default "mode" for this calculator is "Floating Point".

Select the "Calculator Menu > Calculator Mode > Change Mode" command to
change the current mode.  When the Calculator window is active and in an RPN
mode, you can press 'x' to display the current mode in the status bar, and
'm' to change it.  Options include

	Signed Decimal
	Unsigned Decimal
	Unsigned Hexadecimal
	Floating Point
	Equation Editor

All calculations are performed in signed decimal in integer modes.  Floating
point numbers can be entered as -1.0e-5 (use 'Control--' (Control-Minus) to
get the minus sign).  

In Floating Point and Equation Editor modes the 'Display Precision'
preference determines when the stack values are presented in scientific
notation.  Select the "Calculator Menu > Calculator Prefs" menu item to
change this value.

The "Calculate Precision" preference is used internally by the Tcl functions
that perform the operations.

(More information needs to be added for the other RPN modes...)


	  	Equation Editor

When the Calculator mode is "Equation Editor" it is no longer uses RPN, and
the "Value" field no longer maintains a stack.

Instead, you can add an equation in the Input field to have it evaluated
using the Tcl command: expr .  While you are in "Equation Editor" mode all of
the "special" keyboard shortcuts are disabled.  For example, pressing the "m"
key will now insert a real "m" and not offer the dialog to change the
Calculator mode.

The supported mathematical functions in expressions include

	abs acos asin atan atan2 ceil cos cosh double exp floor fmod hypot int
	log log10 pow rand round sin sinh sqrt srand tan tanh wide

Some very simple examples include

	History :

	----------------------------------------------
	1 + abs(-10)    
					11.0
	----------------------------------------------
	rand()          
					0.151567682229
	----------------------------------------------
	rand()          
					0.398035219125
	----------------------------------------------
	(45*90)/10      
					405.0
	----------------------------------------------
	(45*90)/10 + cos(66) 
					404.000352544

The string "$V" (without the quotes) or "$v" or "${V}" or "${v}" will be
substituted with the current Value field, as in

	----------------------------------------------
	1 + 3           
					4.0
	----------------------------------------------
	1 + 3 * $V     
	1 + 3 * 4.0     
					13.0
	----------------------------------------------
	1 + (3 * ${V})  
	1 + (3 * 13.0)  
					40.0
	----------------------------------------------
	${V} + (3 * $V)
	40.0 + (3 * 40.0)   
					160.0


	  	'International' Users

Most of the Keyboard Shortcuts should be automatically adjusted for your
current Alpha "Keyboard" preference.

Preferences: International

If this is not the case, please inform the maintainer of this package about
the changes that need to be made.

Users of non-American keyboards need to type a space after the dead keys to
get ~ and ^.  Note that "," is interpreted as a "."  decimal point for all
calculations.  This reflects the anglo-centrism of Tcl, not Alpha.


	  	What does 'RPN' mean?

In the 1920s, Jan Lukasiewicz developed a formal logic system that allowed
mathematical expressions to be specified without parentheses by placing the
operators before (prefix notation) or after (postfix notation) the operands.
For example the (infix notation) expression

	(4 + 5) * 6


could be expressed in prefix notation as

	* 6 + 4 5

or

	* + 4 5 6


and could be expressed in postfix notation as

	4 5 + 6 *

or

	6 4 5 + *

Prefix notation also came to be known as Polish Notation in honor of
Lukasiewicz.  HP adjusted the postfix notation for a calculator keyboard,
added a stack to hold the operands and functions to reorder the stack.  HP
dubbed the result Reverse Polish Notation (RPN) also in honor of Lukasiewicz.

<http://www.hpmuseum.org/rpn.htm>


	====================================================================

	  	License And Disclaimer

Author: Pete Keleher

Copyright (c) 1996-2005  Pete Keleher, Vince Darley, Craig Barton Upright
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

 ¥ Redistributions of source code must retain the above copyright
   notice, this list of conditions and the following disclaimer.

 ¥ Redistributions in binary form must reproduce the above copyright
   notice, this list of conditions and the following disclaimer in the
   documentation and/or other materials provided with the distribution.

 ¥ Neither the name of Alpha/Alphatk nor the names of its contributors may
   be used to endorse or promote products derived from this software
   without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR
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