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wcalc

NAME

wcalc - a natural-expression command-line calculator

SYNOPSIS

wcalc [ options ] [ expression ... ]

DESCRIPTION

wcalc is a command-line calculator designed to accept all valid mathematical expressions. It supports all standard mathematical operations, parenthesis, brackets, trigonometric functions, hyperbolic trig functions, logs, and boolean operators.

wcalc accepts input in a variety of manners. I it will evaluate If no mathematical expression is given at the commandline, it will evaluate the contents of an environment variable named wcalc_input if one exists. If that variable is not set, wcalc will try to read input from standard input (i.e. piped input). If there is no input from that, wcalc enters "interactive" mode. Interactive mode has more features.

Within wcalc, detailed information about commands, functions, symbols, and variables can be obtained by executing: \explain thing-to-explain

OPTIONS

-H or --help

Prints a help usage message to standard output, then exits.

-E

Specifies that numerical output should be in scientific notation.

-EE

Specifies that numerical output should NOT be in scientific notation.

-PXXX

Sets the precision to be XXX. This setting only affects output, not internal representations. A setting of -1 means formats output in whatever precision seems appropriate.
Precision is set to autoadjust (-1) by default.
Example: wcalc -P6

-v or --version

Prints the version number and exits.

-d or -dec or --decimal

Results are printed in decimal (base 10). This option is the default, and does not have a default prefix to indicate that numbers are in base 10.

-h or -hex or --hexadecimal

Results are printed in hexadecimal (base 16). Numbers printed in hexadecimal have a prefix of 0x unless the -p or --prefixes option is used.

-o or -oct or --octal

Results are printed in octal (base 8). Numbers printed in octal have a prefix of 0 unless the -p or --prefixes option is used.

-b or -bin or --binary

Results are printed in binary (base 2). Numbers printed in binary have a prefix of 0b unless the -p or --prefixes option is used.

-p or --prefixes

Toggles printing prefixes for hexadecimal, octal, and binary forms.

-l or --lenient

Makes the parser assume that uninitialized variables have a value of zero.

-r or --radians

Toggles whether trigonometric functions assume input (and output) is in radians. By default, trigonometric functions assume input is in degrees.

-q or --quiet

Toggles whether the equals sign will be printed before the results.

-c or --conservative

Toggles precision guards. Because of the way floating point numbers are stored, some operations, like 1-.9-.1, can return an extremely small number that is not zero but is less than the official precision of the floating point number and thus for all intents and purposes, it is 0. The precision guard will round numbers to zero if they are less than the official precision of the floating point number. However, sometimes numbers that small or smaller need to be displayed, and thus the precision guard should be turned off.

--remember

Toggles whether or not expressions that produce errors are remembered in the history. Does not affect command-line math.

--round= { none | simple | sig_fig }

Wcalc can attempt to warn you when numbers have been rounded in the output display. It has two methods of keeping track---either by using significant figures (sig_fig), or by a simple digit-counting algorithm. Rounding in the command-line version is denoted by a tilde before the equals sign (~=). Rounding in the GUI version is denoted by changing the text color to red. In some cases, Wcalc may think that the number has been rounded even if it shouldn't have been necessary (this is because of the way floating point numbers are represented internally).

--dsep=X

Sets the decimal separator character to be X.

--tsep=X

Sets the thousands separator character to be X.

--bitsXXXX

Sets the number of bits of precision that will be used to internally represent numbers to be XXXX. The default is 1024. Set higher if you need more precision, set lower if you want to use less memory.

--ints

Toggles whether long integers will be abbreviated or not. This conflicts with engineering notation for large numbers, but not for decimals.

USER-DEFINED VARIABLES

Variables are supported and may be assigned using the = operator. To assign a variable use the form:

foo = anylegalexpression

Thereafter, that variable name is the same as the literal value it represents. Expressions can be stored in variables like this:

foo = 'anylegalexpression'

Expressions stored this way will be interpreted at evaluation time, rather than assignment-time. Note that these cannot be recursive.

All variables may also be stored with a description of what they are. This description is added in the form of a quoted string after the assignment, like this:

foo = 'anylegalexpression' 'description'

ACTIVE VARIABLES

Active variables are designed to give a functionality similar to user-defined functions. They are variables that rather than representing a value, represent an expression that is evaluated whenever the variable is evaluated. This expression may contain other variable names. For example, after the following sequence of commands:

foo=5
bar='foo+4'

The variable bar will evaluate to 9, or four more than whatever foo evaluates to be. These can be stacked, like so:

baz='sin(bar)+foo'

In this case, baz will evaluate to be 5.15643, or the sin of whatever foo+4 is plus whatever foo is.

To demonstrate the utility of these active variables, here are two functions written by Stephen M. Lawson. The first computes the weekday of a given day (dy) in a given month (mo) in a given year (yr). The value it returns is in the range of 1 to 7, where 1 is Sunday, 2 is Monday, 3 is Tuesday, and so forth.

weekday='(((floor((yr - floor(0.6 + 1 / mo)) / 400) - floor((yr - floor(0.6 + 1 / mo)) / 100) + floor((5 * (yr - floor(0.6 + 1 / mo))) / 4) + floor(13 * (mo + 12 * floor(0.6 + 1 / mo) + 1) / 5)) - (7 * floor((floor((yr - floor(0.6 + 1 / mo)) / 400) - floor((yr - floor(0.6 + 1 / mo)) / 100) + floor((5 * (yr - floor(0.6 + 1 / mo))) / 4) + floor(13 * (mo + 12 * floor(0.6 + 1 / mo) + 1) / 5)) / 7)) + 1) + 5 + dy) % 7 + 1'

The second function computes what day Easter will be for a given year (yr) and returns an offset from March 31st. For example, for the year 2005, it returns -4, which means March 27th. Because of leap-year problems, this only works from the year 1900 to 2099, but is a good demonstration nevertheless.

easter='((19 * (yr - 19 * floor(yr / 19)) + 24) - floor((19 * (yr - 19 * floor(yr / 19)) + 24) / 30) * 30) + ((2 * (yr - 4 * floor(yr / 4)) + 4 * (yr - 7 * floor(yr / 7)) + 6 * ((19 * (yr - 19 * floor(yr / 19)) + 24) - floor((19 * (yr - 19 * floor(yr / 19)) + 24) / 30) * 30) + 5) - floor((2 * (yr - 4 * floor(yr / 4)) + 4 * (yr - 7 * floor(yr / 7)) + 6 * ((19 * (yr - 19 * floor(yr / 19)) + 24) - floor((19 * (yr - 19 * floor(yr / 19)) + 24) / 30) * 30) + 5) / 7) * 7) - 9'

BUILT-IN SYMBOLS

There are two basic kinds of built-in symbols in wcalc: functions and constants.

FUNCTIONS

The functions supported in wcalc are almost all self-explanatory. Here are the basic descriptions.

sin cos tan cot

The standard trigonometric functions

asin acos atan acot or arcsin arccos arctan arccot or sin^-1 cos^-1 tan^-1 cot^-1

The standard arc- trigonometric functions.

sinh cosh tanh coth

The standard hyperbolic trigonometric functions.

asinh acosh atanh acoth or arcsinh arccosh arctanh arccoth or sinh^-1 cosh^-1 tanh^-1 coth^-1

The standard arc- hyperbolic trigonometric functions.

log ln logtwo

Log-base-ten, log-base-e and log-base-two, respectively. Remember, you can also construct log-base-X of number Y by computing log(Y)/log(X).

round

Returns the integral value nearest to the argument according to the typical rounding rules.

abs

Returns the absolute value of the argument.

ceil ceiling floor

Returns the ceiling or floor of the argument.

sqrt cbrt

The square and cube root functions.

rand

Returns a random number between 0 and the number given.

irand

Returns a random integer between 0 and the number given.

fact

Returns the factorial of a number.

Gamma

Returns the value of the Gamma function at that value.

lnGamma

Returns the value of the log Gamma function at that value.

zeta

Returns the value of the Riemann zeta function at that value.

sinc

Returns the sinc function (for sinus cardinalis) of the input, also known as the interpolation function, filtering function or the first spherical Bessel function, is the product of a sine function and a monotonically decreasing function.

CONSTANTS

Wcalc supports a lot of constants. Some are special (like pi), and some are simply mathematical or physical constants that have been hardcoded in. The physics constants are taken from http://physics.nist.gov/constants, and should all be in predictable SI units.

The value of pi is special, as it is calculated to however many bits of precision have been specified with the \bits command. The default number of bits is 1024, or a value of:
3.1415926535897932384626433832795028841971693993751058209749445923078164062862089986280348253421170679821480865132823066470938446095505822317253594081284811174502841027019385211055596446229489549303819644288109756659334461284756482337867831652712019091456485669234603486104543266482133936072602491412737245869974724822361502823407955151120558811684656967313093357387193011055974127397801166600823447367841524950037348489795545416453901986117572722731871388422643588974212021713194956805142308399313566247553371620129340026051601856684677033122428187855479365508702723110143458240736806341798963338923286460351089772720817919599675133363110147505797173662675795471777702814318804385560929672479177350549251018537674006123614790110383192502897923367993783619310166679013187969315172579438604030363957033826325935372151289640167976948453904619615481368332936937026831888367580239969088932697527811653282224950410336573385944190516446146423694037380609059088222036945727944116946240616684848934170304346480406820774078369140625

Similarly, all values that rely on the value of pi, like mu0, have the same level of precision. Here is a complete list of the symbols used to represent the constants hardcoded into wcalc:

e

The logarithm constant:
2.718281828459045235360287471352662497757247093699959574966

gamma

Euler's Constant: 0.57721566490153286060651209008240243104215933593992359880576723488486772677766467093694706329174674951463144724980708248096050401448654283622417399764492353625350033374293733773767394279259525824709491600873520394816567

K

Catalan Constant: 0.91596559417721901505460351493238411077414937428167213426649811962176301977625476947935651292611510624857442261919619957903589880332585905943159473748115840699533202877331946051903872747816408786590902

g

Acceleration due to gravity: 9.80665 m/s/s

Cc

Coulomb's Constant: 8987551787.37

Universal Constants

Z0 or Zzero

Impedance of Vacuum: 376.730313461 ohms

epsilon0 or epsilonzero

Permittivity of Free Space: 8.854187817e-12 F/m

mu0 or muzero

Permeability of Free Space calculated as 4*pi*10^-7.

G

Gravitational Constant: 6.67259e-11

h

Planck Constant: 6.6260755e-34

c

Speed of Light: 299792458

Electromagnetic Constants

muB

Bohr Magneton: 5.78838174943e-11 J/T

muN

Nuclear Magneton: 3.15245123824e-14 J/T

G0

Conductance Quantum: 7.748091733e-5 S

ec

Elementary Charge: 1.60217653e-19

Kj

Josephson Constant: 483597.879e9 Hz/V

Rk

Von Klitzing Constant: 25812.807449 omega

Atomic and Nuclear Constants

Malpha

Alpha Particle Mass: 6.6446565e-27 kg

a0

Bohr Radius: 5.291772108e-11 m

Md

Deuteron Mass: 3.34358335e-27 kg

Me

Electron Mass: 9.1093897e-31 kg

re

Electron Radius: 2.817940325e-15 m

eV

Electron Volt: 1.602177250e-12 J

Gf

Fermi Coupling Constant: 1.16638e-5 GeV^-2

alpha

Fine Structure Constant: 7.29735253327e-3

eh

Hartree Energy: 4.35974417e-18 J

Mh

Helion Mass: 5.00641214e-27 kg

Mmu

Muon Mass: 1.88353140e-28 kg

Mn

Neutron Mass: 1.67492728e-27 kg

Mp

Proton Mass: 1.67262171e-27 kg

Rinf

Rydberg Constant: 10973731.568525 1/m

Mt

Tau Mass: 3.16777e-27 kg

Physio-Chemical Constants

u

Atomic Mass Constant: 1.66053886e-27 kg

Na or NA

Avogadro's Constant: 6.0221367e23

k

Boltzmann Constant: 1.3806505e-23

F

Faraday Constant: 96485.3383 C/mol

c1

First Radiation Constant: 3.74177138e-16 W m^2

n0 or nzero

Loschmidt Constant: 2.6867773e25 m^-3

R

Molar Gas Constant: 8.314472

Vm or NAk

Molar Volume of Ideal Gas: 22.413996e-3 (m^3)/mol

c2

Second Radiation Constant: 1.4387752e-2 m K

sigma

Stefan-Boltzmann Constant: 5.670400e-8

b

Wien Displacement Law Constant: 2.8977686e-3 m K

Random Constants

random

A Random Value

irandom

A Random Integer

COMMANDS

There are several commands that are supported in wcalc.

\pXXX

Sets the precision to XXX. This setting only affects output, not internal representations. A setting of -1 means formats output in whatever precision seems appropriate.

\e or \eng or \engineering

Rotates between always using scientific notation, never using scientific notation, and choosing to do scientific notation when convenient. Can also take an argument that is one of always, never, and automatic to choose a mode directly.

\help or ?

Displays a help screen.

\prefs

Prints out the current preference settings.

\li or \list or \listvars

Prints out the currently defined variables.

\r or \radians

Toggles between using and not using radians for trigonometric calculations.

\cons or \conservative

Toggles precision guards. Because of the way floating point numbers are stored, some operations, like 1-.9-.1, can return an extremely small number that is not zero but is less than the official precision of the floating point number and thus for all intents and purposes, it is 0. The precision guard will round numbers to zero if they are less than the official precision of the floating point number. However, sometimes numbers that small or smaller need to be displayed, and thus the precision guard should be turned off.

\p or \picky or \l or \lenient

Toggles variable parsing rules. When wcalc is "picky" it will complain if you use undefined variables. If it is "lenient", wcalc will assume a value of 0 for undefined variables.

\re or \remember or \remember_errors

Toggles whether or not expressions that produce errors are remembered in the history.

\pre or \prefix or \prefixes

Toggles the display of prefixes for hexadecimal, octal, and binary output.

\b or \bin or \binary

Results are printed in binary (base 2). Numbers printed in binary have a prefix of 0b unless the \prefixes command is used.

\d or \dec or \decimal

Results are printed in decimal (base 10). This option is the default, and does not have a default prefix to indicate that numbers are in base 10.

\h or \x or \hex or \hexadecimal

Results are printed in hexadecimal (base 16). Numbers printed in hexadecimal have a prefix of 0x unless the \prefixes command is used.

\o or \oct or \octal

Results are printed in octal (base 8). Numbers printed in octal have a prefix of 0 unless the \prefixes command is used.

\round none|simple|sig_fig

Wcalc can attempt to warn you when numbers have been rounded in the output display. It has two methods of keeping track---either by using significant figures (sig_fig), or by a simple digit-counting algorithm. Rounding in the command-line version is denoted by a tilde before the equals sign (~=). Rounding in the GUI version is denoted by changing the text color to red. In some cases, Wcalc may think that the number has been rounded even if it shouldn't have been necessary (this is because of the way floating point numbers are represented internally).

\dsepX

Sets the decimal separator character to be X.

\tsepX

Sets the thousands-place separator character to be X.

\hlimitX

Sets the limit (X) on the length of the history.

\openXXXXX

Loads file XXXXX.

\saveXXXXX

Saves the history and variable list to a file, XXXXX.

\bitsXXXX

Sets the number of bits of precision that will be used to internally represent numbers to be XXXX. The default is 1024. Set higher if you need more precision, set lower if you want to use less memory.

\ints

Toggles whether long integers will be abbreviated or not. This conflicts with engineering notation for large numbers, but not for decimals.

\prefs or \preferences

Displays the current preference settings.

\convert unit1 unit1

Converts the previous answer from unit1 to unit2.

\store variablename

Saves the specified variable in the preload file, ~/.wcalc_preload

\explain object

Explains the specified object. The object can be a variable, constant, function, or command.

\verbose

Verbose mode displays the expression to be calculated before calculating it.

\del or \delim or \delimiters

Display delimiters in numerical output.

\cmod

Toggle between C-style modulus operation and a more flexible method.

PREFERENCES

Preferences and settings can be retained between invocations of wcalc by storing them in the file ~/.wcalcrc

The format of the file is that each line is either blank or an assignment. Comments are ignored, and are defined as anything to the right of and including a hash mark (#). Assignments are of the form: key=value

The possible keys are:

precision

A number defining the display precision. Equivalent to the \P command, where -1 means "auto" and anything else specifies the number of decimal places. This does not affect the behind-the-scenes precision.

show_equals

Either true ("yes" or "true") or false (anything else). Equivalent to the --quiet argument. Specifies whether answers will begin with an equals sign or not.

engineering

Either "always", "never", or "automatic". Equivalent to the \engineering command. Specifies whether answers will be displayed in engineering notation or not.

use_radians

Either true ("yes" or "true") or false (anything else). Equivalent to the \radians command. Specifies whether trigonometric functions accept input in radians or degrees.

print_prefixes

Either true ("yes" or "true") or false (anything else). Equivalent to the \prefixes command. Specifies whether base prefixes (e.g. 0x for hexadecimal numbers) are used when displaying output.

save_errors

Either true ("yes" or "true") or false (anything else). Equivalent to the \remember_errors command. Specifies whether lines that contain a syntax error are added to the history or not.

precision_guard

Either true ("yes" or "true") or false (anything else). Equivalent to the \conservative command. Specifies whether the display will attempt to eliminate numbers too small to be accurate (hopefully, these are only errors created by the binary approximation of the inputs).

print_integers

Either true ("yes" or "true") or false (anything else). Equivalent to the \ints command. Specifies whether whole integers will be printed un-abbreviated or not. This conflicts with engineering notation for large integers, but not for decimals.

print_delimiters

Either true ("yes" or "true") or false (anything else). Equivalent to the \delimiters command. Specifies whether delimiters will be added to output when displaying.

thousands_delimiter

Uses the next character after the equals sign as its value. Equivalent to the \tsep command. Specifies what the thousands delimiter is, and can affect output if print_delimiters is enabled.

decimal_delimiter

Uses the next character after the equals sign as its value. Equivalent to the \dsep command. Specifies what the decimal delimiter is.

history_limit

Either "no", for no limit, or a number. Equivalent to the \hlimit command.

output_format

Either decimal, octal, binary, hex, or hexadecimal.

rounding_indication

Either no, simple, or sig_fig. Equivalent to the \rounding command.

c_style_mod

Either true ("yes" or "true") or false (anything else). Equivalent to the \cmod command. Specifies whether the modulo operator (%) will behave as it does in the C programming language, or whether it will use a more flexible method. This only affects modulo operations where negative numbers are involved. As an example, with c_style_mod set to true (the default):

-340 % 60 == -40; 340 % -60 == 40; -340 % -60 == -40
However, with c_style_mod set to false:
-340 % 60 == -40; 340 % -60 == -20; -340 % -60 == 20

PRELOAD

Wcalc uses a file, ~/.wcalc_preload, to store persistent information between instances. Typically, this is used to store variables that are frequently defined. This file can be edited by hand with a standard text editor. There is also a command within wcalc (\store) to append a variable definition to the end of this file. Any variable defined in this file is defined and available for use in any subsequent invocation of wcalc.

COPYRIGHT

wcalc is Copyright (C) 2000-2007 Kyle Wheeler.
It is distributed under the GPL, version 2, or (at your option) any later version..

SUGGESTIONS AND BUG REPORTS

Any bugs found should be reported to
Kyle Wheeler at kyle-wcalc@memoryhole.net.