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BC(1) General Commands Manual BC(1) NAME bc - arbitrary-precision arithmetic language SYNOPSIS bc [ -c ] [ -l ] [ file ... ] DESCRIPTION Bc is an interactive processor for a language which resembles 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 syntax for bc pro- grams is as follows; L means letter a-z, E means expression, 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 decimal 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 ) { 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 semicolons or newlines may sep- arate statements. Assignment to scale influences the number of digits to be retained on arithmetic operations in the manner of dc(1). As- signments to ibase or obase set the input and output number radix re- spectively. The same letter may be used as an array, a function, and a simple vari- able simultaneously. All variables are global to the program. `Auto' variables are pushed down during function calls. When using arrays as function arguments or defining them as automatic variables empty square brackets must follow the array name. For 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 exponential function and for(i=1; i<=10; i++) e(i) prints approximate values of the exponential function of the first ten integers. Bc is actually a preprocessor for dc(1), which it invokes automati- cally, unless the -c (compile only) option is present. In this case the dc input is sent to the standard output instead. FILES /usr/lib/lib.b mathematical library dc(1) desk calculator proper SEE ALSO dc(1) L. L. Cherry and R. Morris, BC - An arbitrary precision desk-calculator language BUGS No &&, ||, or ! operators. For statement must have all three E's. Quit is interpreted when read, not when executed. BC(1)