BC(1) BC(1) NAME bc - arbitrary-precision arithmetic language SYNOPSIS bc [ -c ] [ -l ] [ file ... ] DESCRIPTION Bc is an interactive processor for a language which resem- bles C but provides unlimited precision arithmetic. It takes input from any files given, then reads the standard input. The -l argument stands for the name of an arbitrary precision math library. The following syntax for bc pro- grams is like that of C; L means letter a-z, E means expres- sion, S means statement. Comments are enclosed in /* and */. Names simple variables: L array elements: L [ E ] The words `ibase', `obase', and `scale' Other operands arbitrarily long numbers with optional sign and deci- mal point. ( E ) sqrt ( E ) length ( E ) number of significant decimal digits scale ( E ) number of digits right of decimal point L ( E , ... , E ) Operators + - * / % ^ (% is remainder; ^ is power) ++ -- (prefix and postfix; apply to names) == <= >= != < > = += -= *= /= %= ^= Statements E { S ; ... ; S } if ( E ) S while ( E ) S for ( E ; E ; E ) S null statement break quit Function definitions define L ( L , ... , L ) { BC(1) BC(1) auto L , ... , L S ; ... ; S return ( E ) } Functions in -l math library s(x) sine c(x) cosine e(x) exponential l(x) log a(x) arctangent j(n,x) Bessel function All function arguments are passed by value. The value of a statement that is an expression is printed unless the main operator is an assignment. Either semi- colons or newlines may separate statements. Assignment to scale influences the number of digits to be retained on arithmetic operations in the manner of dc(1). Assignments to ibase or obase set the input and output number radix respec- tively. The same letter may be used as an array, a function, and a simple variable simultaneously. All variables are global to the program. `Auto' variables are pushed down during func- tion calls. When using arrays as function arguments or defining them as automatic variables empty square brackets must follow the array name. Bc is actually a preprocessor for dc(1), which it invokes automatically, unless the -c (compile only) option is pre- sent. In this case the dc input is sent to the standard output instead. EXAMPLE scale = 20 define e(x){ auto a, b, c, i, s a = 1 b = 1 s = 1 for(i=1; 1==1; i++){ a = a*x b = b*i c = a/b if(c == 0) return(s) s = s+c } } defines a function to compute an approximate value of the BC(1) BC(1) exponential function and for(i=1; i<=10; i++) e(i) prints approximate values of the exponential function of the first ten integers. FILES /usr/lib/lib.b mathematical library dc(1) desk calculator proper SEE ALSO dc(1), hoc(1) L. L. Cherry and R. Morris, BC - An arbitrary precision desk-calculator language BUGS No &&, oror, or ! operators. For statement must have all three E's. Quit is interpreted when read, not when executed.