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*

**-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.
**-P***XXX*- Sets the "precision",
or the number of decimal places displayed, to be
*XXX*. This setting only affects output, not internal representations. If the precision is set to -1, the number of decimal places displayed will depend on the value.

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 accuracy guards. Because of the way floating point numbers are stored in computers, some numbers cannot be represented exactly (such as 0.1). Because of this, calculating with those numbers can produce results that are not exactly correct, but are different from the correct answer by a very small value (smaller than the floating point value can represent accurately). For example, the calculation of 1-.9-.1 can return an extremely small number that is not zero but is less than what can be represented accurately, and thus for all intents and purposes, it is 0. The accuracy guard feature will round numbers to zero if they are less than the representable accuracy of the floating point number. However, sometimes numbers that small or smaller need to be displayed, and thus the accuracy guard should be turned off. Alternatively, the number of internal bits could be increased, which makes it possible to represent numbers with more accuracy.
**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.
**idsep=***X*- Sets the input-only decimal separator character to be X.
**itsep=***X*- Sets the input-only thousands separator character to be X.
**bits***XXXX*- Sets the number of bits of memory
that will be used to internally represent numbers to be
*XXXX*. The default is 1024. Set higher if you need to work with extremely large or extremely small numbers, 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.

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’

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’

**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.

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

**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

**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

**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

**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**- A Random Value
**irandom**- A Random Integer

**\p***XXX*- Sets
the "precision", or the number of decimal places displayed, to be
*XXX*. This setting only affects output, not internal representations. If the precision is set to -1, the number of decimal places displayed will depend on the value. The default is -1. **\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 accuracy guards. Because of the way floating point numbers are stored in computers, some numbers cannot be represented exactly (such as 0.1). Because of this, calculating with those numbers can produce results that are not exactly correct, but are different from the correct answer by a very small value (smaller than the floating point value can represent accurately). For example, the calculation of 1-.9-.1 can return an extremely small number that is not zero but is less than what can be represented accurately, and thus for all intents and purposes, it is 0. The accuracy guard feature will round numbers to zero if they are less than the representable accuracy of the floating point number. However, sometimes numbers that small or smaller need to be displayed, and thus the accuracy guard should be turned off. Alternatively, the number of internal bits could be increased, which makes it possible to represent numbers with more accuracy.
**\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).
**\dsep***X*- Sets the decimal separator character to be
*X*. **\tsep***X*- Sets
the thousands-place separator character to be
*X*. **\idsep***X*- Sets the input-only
decimal separator character to be
*X*. **\itsep***X*- Sets the input-only thousands-place
separator character to be
*X*. **\hlimit***X*- Sets the limit (
*X*) on the length of the history. **\open***XXXXX*- Loads file
*XXXXX*. **\save***XXXXX*- Saves the history and
variable list to a file,
*XXXXX*. **\bits***XXXX*- 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.

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. **input_thousands_delimiter**- Uses the next character
after the equals sign as its value. Equivalent to the
**\itsep**command. Specifies what the input-only thousands delimiter is, and cannot affect output. **input_decimal_delimiter**- Uses the next character after the equals sign as its value. Equivalent to
the
**\idsep**command. Specifies what the input-only decimal delimiter is, and cannot affect output. **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

It is distributed under the GPL, version 2, or (at your option) any later version..

Kyle Wheeler at