1.\" $OpenBSD: bc.1,v 1.22 2007/05/31 19:20:07 jmc Exp $ 2.\" 3.\" Copyright (C) Caldera International Inc. 2001-2002. 4.\" All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code and documentation must retain the above 10.\" copyright notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 3. All advertising materials mentioning features or use of this software 15.\" must display the following acknowledgement: 16.\" This product includes software developed or owned by Caldera 17.\" International, Inc. 18.\" 4. Neither the name of Caldera International, Inc. nor the names of other 19.\" contributors may be used to endorse or promote products derived from 20.\" this software without specific prior written permission. 21.\" 22.\" USE OF THE SOFTWARE PROVIDED FOR UNDER THIS LICENSE BY CALDERA 23.\" INTERNATIONAL, INC. AND CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR 24.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 25.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 26.\" IN NO EVENT SHALL CALDERA INTERNATIONAL, INC. BE LIABLE FOR ANY DIRECT, 27.\" INDIRECT INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 28.\" (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR 29.\" SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 31.\" STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING 32.\" IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 33.\" POSSIBILITY OF SUCH DAMAGE. 34.\" 35.\" @(#)bc.1 6.8 (Berkeley) 8/8/91 36.\" 37.Dd November 14, 2009 38.Dt BC 1 39.Os 40.Sh NAME 41.Nm bc 42.Nd arbitrary-precision arithmetic language and calculator 43.Sh SYNOPSIS 44.Nm 45.Op Fl cl 46.Op Fl e Ar expression 47.Op Ar file ... 48.Sh DESCRIPTION 49.Nm 50is an interactive processor for a language which resembles 51C but provides unlimited precision arithmetic. 52It takes input from any expressions on the command line and 53any files given, then reads the standard input. 54.Pp 55Options available: 56.Bl -tag -width Ds 57.It Fl c 58.Nm 59is actually a preprocessor for 60.Xr dc 1 , 61which it invokes automatically, unless the 62.Fl c 63.Pq compile only 64option is present. 65In this case the generated 66.Xr dc 1 67instructions are sent to the standard output, 68instead of being interpreted by a running 69.Xr dc 1 70process. 71.It Fl e Ar expression 72Evaluate 73.Ar expression . 74If multiple 75.Fl e 76options are specified, they are processed in the order given, 77separated by newlines. 78.It Fl l 79Allow specification of an arbitrary precision math library. 80The definitions in the library are available to command line 81expressions. 82.El 83.Pp 84The syntax for 85.Nm 86programs is as follows: 87.Sq L 88means letter a-z; 89.Sq E 90means expression; 91.Sq S 92means statement. 93As a non-portable extension, it is possible to use long names 94in addition to single letter names. 95A long name is a sequence starting with a lowercase letter 96followed by any number of lowercase letters and digits. 97The underscore character 98.Pq Sq _ 99counts as a letter. 100.Pp 101Comments 102.Bd -unfilled -offset indent -compact 103are enclosed in /* and */ 104are enclosed in # and the next newline 105.Ed 106.Pp 107The newline is not part of the line comment, 108which in itself is a non-portable extension. 109.Pp 110Names 111.Bd -unfilled -offset indent -compact 112simple variables: L 113array elements: L [ E ] 114The words `ibase', `obase', and `scale' 115The word `last' or a single dot 116.Ed 117.Pp 118Other operands 119.Bd -unfilled -offset indent -compact 120arbitrarily long numbers with optional sign and decimal point 121( E ) 122sqrt ( E ) 123length ( E ) number of significant decimal digits 124scale ( E ) number of digits right of decimal point 125L ( E , ... , E ) 126.Ed 127.Pp 128The sequence 129.Sq \e<newline><whitespace> 130is ignored within numbers. 131.Pp 132Operators 133.Pp 134The following arithmetic and logical operators can be used. 135The semantics of the operators is the same as in the C language. 136They are listed in order of decreasing precedence. 137Operators in the same group have the same precedence. 138.Bl -column "= += \-= *= /= %= ^=" "Associativity" "multiply, divide, modulus" -offset indent 139.It Sy "Operator" Ta Sy "Associativity" Ta Sy "Description" 140.It "++ \-\-" Ta "none" Ta "increment, decrement" 141.It "\-" Ta "none" Ta "unary minus" 142.It "^" Ta "right" Ta "power" 143.It "* / %" Ta "left" Ta "multiply, divide, modulus" 144.It "+ \-" Ta "left" Ta "plus, minus" 145.It "= += -= *= /= %= ^=" Ta "right" Ta "assignment" 146.It "== <= >= != < >" Ta "none" Ta "relational" 147.It "!" Ta "none" Ta "boolean not" 148.It "&&" Ta "left" Ta "boolean and" 149.It "||" Ta "left" Ta "boolean or" 150.El 151.Pp 152Note the following: 153.Bl -bullet -offset indent 154.It 155The relational operators may appear in any expression. 156The 157.St -p1003.2 158standard only allows them in the conditional expression of an 159.Sq if , 160.Sq while 161or 162.Sq for 163statement. 164.It 165The relational operators have a lower precedence than the assignment 166operators. 167This has the consequence that the expression 168.Sy a = b < c 169is interpreted as 170.Sy (a = b) < c , 171which is probably not what the programmer intended. 172.It 173In contrast with the C language, the relational operators all have 174the same precedence, and are non-associative. 175The expression 176.Sy a < b < c 177will produce a syntax error. 178.It 179The boolean operators (!, && and ||) are non-portable extensions. 180.It 181The boolean not 182(!) operator has much lower precedence than the same operator in the 183C language. 184This has the consequence that the expression 185.Sy !a < b 186is interpreted as 187.Sy !(a < b) . 188Prudent programmers use parentheses when writing expressions involving 189boolean operators. 190.El 191.Pp 192Statements 193.Bd -unfilled -offset indent -compact 194E 195{ S ; ... ; S } 196if ( E ) S 197if ( E ) S else S 198while ( E ) S 199for ( E ; E ; E ) S 200null statement 201break 202continue 203quit 204a string of characters, enclosed in double quotes 205print E ,..., E 206.Ed 207.Pp 208A string may contain any character, except a double quote. 209The if statement with an else branch is a non-portable extension. 210All three E's in a for statement may be empty. 211This is a non-portable extension. 212The continue and print statements are also non-portable extensions. 213.Pp 214The print statement takes a list of comma-separated expressions. 215Each expression in the list is evaluated and the computed 216value is printed and assigned to the variable `last'. 217No trailing newline is printed. 218The expression may also be a string enclosed in double quotes. 219Within these strings the following escape sequences may be used: 220.Sq \ea 221for bell (alert), 222.Sq \eb 223for backspace, 224.Sq \ef 225for formfeed, 226.Sq \en 227for newline, 228.Sq \er 229for carriage return, 230.Sq \et 231for tab, 232.Sq \eq 233for double quote and 234.Sq \e\e 235for backslash. 236Any other character following a backslash will be ignored. 237Strings will not be assigned to `last'. 238.Pp 239Function definitions 240.Bd -unfilled -offset indent 241define L ( L ,..., L ) { 242 auto L, ... , L 243 S; ... S 244 return ( E ) 245} 246.Ed 247.Pp 248As a non-portable extension, the opening brace of the define statement 249may appear on the next line. 250The return statement may also appear in the following forms: 251.Bd -unfilled -offset indent 252return 253return () 254return E 255.Ed 256.Pp 257The first two are equivalent to the statement 258.Dq return 0 . 259The last form is a non-portable extension. 260Not specifying a return statement is equivalent to writing 261.Dq return (0) . 262.Pp 263Functions available in the math library, which is loaded by specifying the 264.Fl l 265flag on the command line 266.Pp 267.Bl -tag -width j(n,x) -offset indent -compact 268.It s(x) 269sine 270.It c(x) 271cosine 272.It e(x) 273exponential 274.It l(x) 275log 276.It a(x) 277arctangent 278.It j(n,x) 279Bessel function 280.El 281.Pp 282All function arguments are passed by value. 283.Pp 284The value of a statement that is an expression is printed 285unless the main operator is an assignment. 286The value printed is assigned to the special variable `last'. 287This is a non-portable extension. 288A single dot may be used as a synonym for `last'. 289Either semicolons or newlines may separate statements. 290Assignment to 291.Ar scale 292influences the number of digits to be retained on arithmetic 293operations in the manner of 294.Xr dc 1 . 295Assignments to 296.Ar ibase 297or 298.Ar obase 299set the input and output number radix respectively. 300.Pp 301The same letter may be used as an array, a function, 302and a simple variable simultaneously. 303All variables are global to the program. 304`Auto' variables are pushed down during function calls. 305When using arrays as function arguments 306or defining them as automatic variables, 307empty square brackets must follow the array name. 308.Pp 309For example 310.Bd -literal -offset indent 311scale = 20 312define e(x){ 313 auto a, b, c, i, s 314 a = 1 315 b = 1 316 s = 1 317 for(i=1; 1==1; i++){ 318 a = a*x 319 b = b*i 320 c = a/b 321 if(c == 0) return(s) 322 s = s+c 323 } 324} 325.Ed 326.Pp 327defines a function to compute an approximate value of 328the exponential function and 329.Pp 330.Dl for(i=1; i<=10; i++) e(i) 331.Pp 332prints approximate values of the exponential function of 333the first ten integers. 334.Bd -literal -offset indent 335$ bc -l -e 'scale = 500; 2 * a(2^10000)' -e quit 336.Ed 337prints an approximation of pi. 338.Sh FILES 339.Bl -tag -width /usr/share/misc/bc.library -compact 340.It Pa /usr/share/misc/bc.library 341math library, read when the 342.Fl l 343option is specified on the command line. 344.El 345.Sh SEE ALSO 346.Xr dc 1 347.Rs 348.%A "Lorinda Cherry" 349.%A "Robert Morris" 350.%B "4.4BSD Users's Supplementary Documents (USD)" 351.%T "BC \- An Arbitrary Precision Desk-Calculator Language" 352.Re 353.Sh STANDARDS 354The 355.Nm 356utility is compliant with the 357.St -p1003.1-2004 358specification. 359.Pp 360The flags 361.Op Fl ce 362are extensions to that specification. 363.Sh HISTORY 364The 365.Nm 366command first appeared in 367.At v6 . 368A complete rewrite of the 369.Nm 370command first appeared in 371.Ox 3.5 . 372.Sh AUTHORS 373.An -nosplit 374The original version of the 375.Nm 376command was written by 377.An Robert Morris 378and 379.An Lorinda Cherry . 380The current version of the 381.Nm 382utility was written by 383.An Otto Moerbeek . 384.Sh BUGS 385.Ql Quit 386is interpreted when read, not when executed. 387.Pp 388Some non-portable extensions, as found in the GNU version of the 389.Nm 390utility are not implemented (yet). 391