# bc(1) [plan9 man page]

BC(1) General Commands Manual BC(1)NAME

bc - arbitrary-precision arithmetic languageSYNOPSIS

bc [] [-c] [ file ... ]-lDESCRIPTION

Bc is an interactive processor for a language that resembles C but provides arithmetic on numbers of arbitrary length with up to 100 digits right of the decimal point. It takes input from any files given, then reads the standard input. Theargument stands for the name of an arbitrary precision math library. The following syntax for bc programs is like that of C; L means letter a-z, E means expression, S means statement. Lexical comments are enclosed in /* */ newlines end statements 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) function call Operators + - * / % ^ (% is remainder; ^ is power) ++-l== <= >= != < > = +=--*= /= %= ^= Statements E { S ; ... ; S } print E if ( E ) S while ( E ) S for ( E ; E ; E ) S null statement break quit "text" Function definitions define L ( L , ... , L ){ auto L , ... , L S ; ... ; S return E } Functions in-=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 an expression at the top level is printed unless the main operator is an assignment. Text in quotes, which may include new- lines, is also printed. Either semicolons 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- matic variables are pushed down during function calls. In a declaration of an array as a function argument or automatic variable empty square brackets must follow the array name. Bc is actually a preprocessor for dc(1), which it invokes automatically, unless the-l(compile only) option is present. In this case the dc input is sent to the standard output instead.-cEXAMPLE

Define a function to compute an approximate value of the exponential. Use it to print 10 values. (The exponential function in the library gives better answers.) scale = 20 define e(x) { auto a, b, c, i, s a = 1 b = 1 s = 1 for(i=1; 1; i++) { a *= x b *= i c = a/b if(c == 0) return s s += c } } for(i=1; i<=10; i++) print e(i)FILES

/sys/lib/bclib mathematical librarySOURCE

/sys/src/cmd/bc.ySEE ALSO

dc(1), hoc(1)BUGS

No or operators. A statement must have all three A is interpreted when read, not when executed. BC(1)

## Check Out this Related Man Page

bc(1) User Commands bc(1)NAME

bc - arbitrary precision arithmetic languageSYNOPSIS

/usr/bin/bc [] [-c] [file]... /usr/xpg6/bin/bc [-l] [-c] [file]...-lDESCRIPTION

The bc utility implements an arbitrary precision calculator. It takes input from any files given, then reads from the standard input. If the standard input and standard output to bc are attached to a terminal, the invocation of bc is interactive, causing behavioral con- straints described in the following sections. bc processes a language that resembles C and is a preprocessor for the desk calculator pro- gram dc, which it invokes automatically unless theoption is specified. In this case the dc input is sent to the standard output instead.-cUSAGE

The syntax for bc programs is as follows: L Means a letter a-z, E Means an expression: a (mathematical or logical) value, an operand that takes a value, or a combination of operands and operators that evaluates to a value, S Means a statement. Comments Enclosed in /* and */. Names (Operands) Simple variables: L. Array elements: L [ E ] (up to BC_DIM_MAX dimensions). The words ibase, obase (limited to BC_BASE_MAX), and scale (limited to BC_SCALE_MAX). Other Operands Arbitrarily long numbers with optional sign and decimal point. Strings of fewer than BC_STRING_MAX characters, between double quotes ("). ( E ) sqrt ( E ) Square root 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 .string Function Definitions define L ( L ,..., L ) { auto L ,..., L S ;... S return ( E ) } Functions in--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 new-lines may separate statements. Assignment to scale influences the number of digits to be retained on arithmetic operations in the manner of dc. Assignments to ibase or obase set the input and output number radix respectively. 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 stacked during function calls. When using arrays as function arguments or defining them as automatic variables, empty square brackets must follow the array name.-lOPTIONS

The following operands are supported:Compiles only. The output is dc commands that are sent to the standard output. /usr/bin/bc-cDefines the math functions and initializes scale to 20, instead of the default zero. /usr/xpg6/bin/bc-lDefines the math functions and initializes scale to 20, instead of the default zero. All math results have the scale of 20.-lOPERANDS

The following operands are supported: file A pathname of a text file containing bc program statements. After all cases of file have been read, bc reads the standard input.EXAMPLES

Example 1 Setting the precision of a variable In the shell, the following assigns an approximation of the first ten digits of n to the variable x: x=$(printf "%s " 'scale = 10; 104348/33215' | bc) Example 2 Defining a computing function Defines a function to compute an approximate value of the exponential function: 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 } } Example 3 Printing the approximate values of the function Prints approximate values of the exponential function of the first ten integers: for(i=1; i<=10; i++) e(i) or for (i = 1; i <= 10; ++i) { e(i) }ENVIRONMENT VARIABLES

See environ(5) for descriptions of the following environment variables that affect the execution of bc: LANG, LC_ALL, LC_CTYPE, LC_MES- SAGES, and NLSPATH.EXIT STATUS

The following exit values are returned: 0 All input files were processed successfully. unspecified An error occurred.FILES

/usr/lib/lib.b mathematical library /usr/include/limits.h to define BC_ parametersATTRIBUTES

See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Availability |SUNWesu | +-----------------------------+-----------------------------+ |Interface Stability |Standard | +-----------------------------+-----------------------------+SEE ALSO

dc(1), awk(1), attributes(5), environ(5), standards(5)NOTES

The bc command does not recognize the logical operators && and ||. The for statement must have all three expressions (E's).SunOS 5.1129 Aug 2003 bc(1)