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bc(1)                                                                                                  bc(1)



NAME
       bc - An arbitrary precision calculator language

SYNTAX
       bc [ -hlwsqv ] [long-options] [  file ... ]

VERSION
       This man page documents GNU bc version 1.06.

DESCRIPTION
       bc  is a language that supports arbitrary precision numbers with interactive execution of statements.
       There are some similarities in the syntax to the C programming language.  A standard math library  is
       available  by  command  line option.  If requested, the math library is defined before processing any
       files.  bc starts by processing code from all the files listed on  the  command  line  in  the  order
       listed.  After all files have been processed, bc reads from the standard input.  All code is executed
       as it is read.  (If a file contains a command to halt the processor, bc  will  never  read  from  the
       standard input.)

       This  version  of  bc contains several extensions beyond traditional bc implementations and the POSIX
       draft standard.  Command line options can cause  these  extensions  to  print  a  warning  or  to  be
       rejected.  This document describes the language accepted by this processor.  Extensions will be iden-tified identified
       tified as such.

   OPTIONS
       -h, --help
              Print the usage and exit.

       -i, --interactive
              Force interactive mode.

       -l, --mathlib
              Define the standard math library.

       -w, --warn
              Give warnings for extensions to POSIX bc.

       -s, --standard
              Process exactly the POSIX bc language.

       -q, --quiet
              Do not print the normal GNU bc welcome.

       -v, --version
              Print the version number and copyright and quit.

   NUMBERS
       The most basic element in bc is the number.  Numbers are arbitrary precision numbers.  This precision
       is both in the integer part and the fractional part.  All numbers are represented internally in deci-mal decimal
       mal and all computation is done in decimal.  (This version truncates results from divide and multiply
       operations.)  There are two attributes of numbers, the length and the scale.  The length is the total
       number of significant decimal digits in a number and the scale is the total number of decimal  digits
       after the decimal point.  For example:
               .000001 has a length of 6 and scale of 6.
               1935.000 has a length of 7 and a scale of 3.

   VARIABLES
       Numbers are stored in two types of variables, simple variables and arrays.  Both simple variables and
       array variables are named.  Names begin with a letter followed by any number of letters,  digits  and
       underscores.   All  letters must be lower case.  (Full alpha-numeric names are an extension. In POSIX
       bc all names are a single lower case letter.)  The type of variable is clear by the  context  because
       all array variable names will be followed by brackets ([]).

       There  are  four special variables, scale, ibase, obase, and last.  scale defines how some operations
       use digits after the decimal point.  The default value of scale is 0. ibase and obase define the con-version conversion
       version  base  for input and output numbers.  The default for both input and output is base 10.  last
       (an extension) is a variable that has the value of the last printed number.  These will be  discussed
       in further detail where appropriate.  All of these variables may have values assigned to them as well
       as used in expressions.

   COMMENTS
       Comments in bc start with the characters /* and end with the characters */.  Comments may start  any-where anywhere
       where and appear as a single space in the input.  (This causes comments to delimit other input items.
       For example, a comment can not be found in the middle of a variable name.)  Comments include any new-lines newlines
       lines (end of line) between the start and the end of the comment.

       To support the use of scripts for bc, a single line comment has been added as an extension.  A single
       line comment starts at a # character and continues to the next end of the  line.   The  end  of  line
       character is not part of the comment and is processed normally.

   EXPRESSIONS
       The  numbers  are  manipulated  by expressions and statements.  Since the language was designed to be
       interactive, statements and expressions are executed as soon as possible.  There is  no  "main"  pro-gram. program.
       gram.   Instead,  code  is executed as it is encountered.  (Functions, discussed in detail later, are
       defined when encountered.)

       A simple expression is just a constant. bc converts constants into internal decimal numbers using the
       current input base, specified by the variable ibase. (There is an exception in functions.)  The legal
       values of ibase are 2 through 16.  Assigning a value outside this range to ibase  will  result  in  a
       value  of  2  or 16.  Input numbers may contain the characters 0-9 and A-F. (Note: They must be capi-tals. capitals.
       tals.  Lower case letters are variable names.)  Single digit numbers always have  the  value  of  the
       digit regardless of the value of ibase. (i.e. A = 10.)  For multi-digit numbers, bc changes all input
       digits greater or equal to ibase to the value of ibase-1.  This makes the number FFF  always  be  the
       largest 3 digit number of the input base.

       Full  expressions  are  similar  to many other high level languages.  Since there is only one kind of
       number, there are no rules for mixing types.  Instead, there are rules on the scale  of  expressions.
       Every expression has a scale.  This is derived from the scale of original numbers, the operation per-formed performed
       formed and in many cases, the value of the variable scale. Legal values of the variable scale  are  0
       to the maximum number representable by a C integer.

       In  the following descriptions of legal expressions, "expr" refers to a complete expression and "var"
       refers to a simple or an array variable.  A simple variable is just a
              name
       and an array variable is specified as
              name[expr]
       Unless specifically mentioned the scale of the  result  is  the  maximum  scale  of  the  expressions
       involved.

       - expr The result is the negation of the expression.

       ++ var The variable is incremented by one and the new value is the result of the expression.

       -- var The variable is decremented by one and the new value is the result of the expression.

       var ++   The  result  of  the expression is the value of the variable and then the variable is incre-mented incremented
              mented by one.

       var -- The result of the expression is the value of the variable and then the variable is decremented
              by one.

       expr + expr
              The result of the expression is the sum of the two expressions.

       expr - expr
              The result of the expression is the difference of the two expressions.

       expr * expr
              The result of the expression is the product of the two expressions.

       expr / expr
              The  result of the expression is the quotient of the two expressions.  The scale of the result
              is the value of the variable scale.

       expr % expr
              The result of the expression is the "remainder" and it is computed in the following  way.   To
              compute  a%b, first a/b is computed to scale digits.  That result is used to compute a-(a/b)*b
              to the scale of the maximum of scale+scale(b) and scale(a).  If scale is set to zero and  both
              expressions are integers this expression is the integer remainder function.

       expr ^ expr
              The  result  of  the  expression  is  the  value of the first raised to the second. The second
              expression must be an integer.  (If the second expression is not an integer, a warning is gen-erated generated
              erated  and  the expression is truncated to get an integer value.)  The scale of the result is
              scale if the exponent is negative.  If the exponent is positive the scale of the result is the
              minimum  of  the scale of the first expression times the value of the exponent and the maximum
              of scale and the scale of the first  expression.   (e.g.  scale(a^b)  =  min(scale(a)*b,  max(
              scale, scale(a))).)  It should be noted that expr^0 will always return the value of 1.

       ( expr )
              This alters the standard precedence to force the evaluation of the expression.

       var = expr
              The variable is assigned the value of the expression.

       var <op>= expr
              This  is  equivalent to "var = var <op> expr" with the exception that the "var" part is evalu-ated evaluated
              ated only once.  This can make a difference if "var" is an array.

        Relational expressions are a special kind of expression that always evaluate to 0 or  1,  0  if  the
       relation  is  false and 1 if the relation is true.  These may appear in any legal expression.  (POSIX
       bc requires that relational expressions are used only in if, while, and for statements and that  only
       one relational test may be done in them.)  The relational operators are

       expr1 < expr2
              The result is 1 if expr1 is strictly less than expr2.

       expr1 <= expr2
              The result is 1 if expr1 is less than or equal to expr2.

       expr1 > expr2
              The result is 1 if expr1 is strictly greater than expr2.

       expr1 >= expr2
              The result is 1 if expr1 is greater than or equal to expr2.

       expr1 == expr2
              The result is 1 if expr1 is equal to expr2.

       expr1 != expr2
              The result is 1 if expr1 is not equal to expr2.

       Boolean  operations  are  also legal.  (POSIX bc does NOT have boolean operations). The result of all
       boolean operations are 0 and 1 (for false and true) as in relational expressions.  The boolean opera-tors operators
       tors are:

       !expr  The result is 1 if expr is 0.

       expr && expr
              The result is 1 if both expressions are non-zero.

       expr || expr
              The result is 1 if either expression is non-zero.

       The expression precedence is as follows: (lowest to highest)
              || operator, left associative
              && operator, left associative
              ! operator, nonassociative
              Relational operators, left associative
              Assignment operator, right associative
              + and - operators, left associative
              *, / and % operators, left associative
              ^ operator, right associative
              unary - operator, nonassociative
              ++ and -- operators, nonassociative

       This  precedence  was  chosen so that POSIX compliant bc programs will run correctly. This will cause
       the use of the relational and logical operators to have some unusual behavior when used with  assign-ment assignment
       ment expressions.  Consider the expression:
              a = 3 < 5

       Most C programmers would assume this would assign the result of "3 < 5" (the value 1) to the variable
       "a".  What this does in bc is assign the value 3 to the variable "a" and then compare 3 to 5.  It  is
       best to use parenthesis when using relational and logical operators with the assignment operators.

       There are a few more special expressions that are provided in bc.  These have to do with user defined
       functions and standard functions.  They all appear as "name(parameters)".  See the section  on  func-
       tions for user defined functions.  The standard functions are:

       length ( expression )
              The value of the length function is the number of significant digits in the expression.

       read ( )
              The  read  function  (an  extension) will read a number from the standard input, regardless of
              where the function occurs.   Beware, this can cause problems with the mixing of data and  pro-gram program
              gram in the standard input.  The best use for this function is in a previously written program
              that needs input from the user, but never allows program code to be input from the user.   The
              value  of the read function is the number read from the standard input using the current value
              of the variable ibase for the conversion base.

       scale ( expression )
              The value of the scale function is the number of digits after the decimal point in the expres-sion. expression.
              sion.

       sqrt ( expression )
              The  value  of  the  sqrt function is the square root of the expression.  If the expression is
              negative, a run time error is generated.

   STATEMENTS
       Statements (as in most algebraic languages) provide the sequencing of expression evaluation.   In  bc
       statements  are  executed "as soon as possible."  Execution happens when a newline in encountered and
       there is one or more complete statements.  Due to this immediate execution, newlines are very  impor-tant important
       tant  in bc. In fact, both a semicolon and a newline are used as statement separators.  An improperly
       placed newline will cause a syntax error.  Because newlines are statement separators, it is  possible
       to  hide a newline by using the backslash character.  The sequence "\<nl>", where <nl> is the newline
       appears to bc as whitespace instead of a newline.  A statement list is a series of  statements  sepa-rated separated
       rated by semicolons and newlines.  The following is a list of bc statements and what they do: (Things
       enclosed in brackets ([]) are optional parts of the statement.)

       expression
              This statement does one of two things.  If the expression starts with "<variable> <assignment>
              ...",  it is considered to be an assignment statement.  If the expression is not an assignment
              statement, the expression is evaluated and  printed  to  the  output.   After  the  number  is
              printed,  a  newline is printed.  For example, "a=1" is an assignment statement and "(a=1)" is
              an expression that has an embedded assignment.  All numbers that are printed  are  printed  in
              the  base  specified  by  the  variable  obase.  The  legal  values  for  obase  are 2 through
              BC_BASE_MAX.  (See the section LIMITS.)  For bases 2 through 16, the usual method  of  writing
              numbers  is used.  For bases greater than 16, bc uses a multi-character digit method of print-ing printing
              ing the numbers where each higher base digit is printed as a base 10 number.  The  multi-char-acter multi-character
              acter  digits  are separated by spaces.  Each digit contains the number of characters required
              to represent the base ten value of "obase-1".  Since numbers are of arbitrary precision,  some
              numbers may not be printable on a single output line.  These long numbers will be split across
              lines using the "\" as the last character on a line.  The maximum number of characters printed
              per line is 70.  Due to the interactive nature of bc, printing a number causes the side effect
              of assigning the printed value to the special variable last. This allows the user  to  recover
              the  last  value  printed  without  having  to  retype the expression that printed the number.
              Assigning to last is legal and will overwrite the last printed value with the assigned  value.
              The  newly  assigned  value  will  remain until the next number is printed or another value is
              assigned to last.  (Some installations may allow the use of a single period (.) which  is  not
              part of a number as a short hand notation for for last.)

       string The  string is printed to the output.  Strings start with a double quote character and contain
              all characters until the next double quote character.   All  characters  are  take  literally,
              including any newline.  No newline character is printed after the string.

       print list
              The print statement (an extension) provides another method of output.  The "list" is a list of
              strings and expressions separated by commas.  Each string or  expression  is  printed  in  the
              order  of  the  list.  No terminating newline is printed.  Expressions are evaluated and their
              value is printed and assigned to the variable last. Strings in the print statement are printed
              to the output and may contain special characters.  Special characters start with the backslash
              character (\).  The special  characters  recognized  by  bc  are  "a"  (alert  or  bell),  "b"
              (backspace),  "f"  (form  feed), "n" (newline), "r" (carriage return), "q" (double quote), "t"
              (tab), and "\" (backslash).  Any other character following the backslash will be ignored.

       { statement_list }
              This is the compound statement.  It allows multiple statements to be grouped together for exe-cution. execution.
              cution.

       if ( expression ) statement1 [else statement2]
              The  if  statement evaluates the expression and executes statement1 or statement2 depending on
              the value of the expression.  If the expression  is  non-zero,  statement1  is  executed.   If
              statement2 is present and the value of the expression is 0, then statement2 is executed.  (The
              else clause is an extension.)

       while ( expression ) statement
              The while statement will execute the statement while the expression is non-zero.  It evaluates
              the  expression before each execution of the statement.   Termination of the loop is caused by
              a zero expression value or the execution of a break statement.

       for ( [expression1] ; [expression2] ; [expression3] ) statement
              The for statement controls repeated execution of  the  statement.   Expression1  is  evaluated
              before  the  loop.  Expression2 is evaluated before each execution of the statement.  If it is
              non-zero, the statement is evaluated.  If it is zero, the loop is terminated.  After each exe-cution execution
              cution  of the statement, expression3 is evaluated before the reevaluation of expression2.  If
              expression1 or expression3 are missing, nothing is evaluated at the point they would be evalu-ated. evaluated.
              ated.   If expression2 is missing, it is the same as substituting the value 1 for expression2.
              (The optional expressions are an extension. POSIX bc requires  all  three  expressions.)   The
              following is equivalent code for the for statement:
              expression1;
              while (expression2) {
                 statement;
                 expression3;
              }

       break  This statement causes a forced exit of the most recent enclosing while statement or for state-ment. statement.
              ment.

       continue
              The continue statement (an extension)  causes the most recent enclosing for statement to start
              the next iteration.

       halt   The  halt  statement  (an  extension) is an executed statement that causes the bc processor to
              quit only when it is executed.  For example, "if (0 == 1) halt" will not cause bc to terminate
              because the halt is not executed.

       return Return the value 0 from a function.  (See the section on functions.)

       return ( expression )
              Return  the  value  of the expression from a function.  (See the section on functions.)  As an
              extension, the parenthesis are not required.

   PSEUDO STATEMENTS
       These statements are not statements in the traditional sense.   They  are  not  executed  statements.
       Their function is performed at "compile" time.

       limits Print the local limits enforced by the local version of bc.  This is an extension.

       quit   When  the quit statement is read, the bc processor is terminated, regardless of where the quit
              statement is found.  For example, "if (0 == 1) quit" will cause bc to terminate.

       warranty
              Print a longer warranty notice.  This is an extension.

   FUNCTIONS
       Functions provide a method of defining a computation that can be executed  later.   Functions  in  bc
       always  compute a value and return it to the caller.  Function definitions are "dynamic" in the sense
       that a function is undefined until a definition is encountered in the input.  That definition is then
       used  until  another  definition  function for the same name is encountered.  The new definition then
       replaces the older definition.  A function is defined as follows:
              define name ( parameters ) { newline
                  auto_list   statement_list }
       A function call is just an expression of the form "name(parameters)".

       Parameters are numbers or arrays (an extension).  In the function definition, zero or more parameters
       are  defined  by listing their names separated by commas.  Numbers are only call by value parameters.
       Arrays are only call by variable.  Arrays are specified in the parameter definition by  the  notation
       "name[]".    In the function call, actual parameters are full expressions for number parameters.  The
       same notation is used for passing arrays as for defining array parameters.  The named array is passed
       by variable to the function.  Since function definitions are dynamic, parameter numbers and types are
       checked when a function is called.  Any mismatch in number or types of parameters will cause  a  run-time runtime
       time error.  A runtime error will also occur for the call to an undefined function.

       The auto_list is an optional list of variables that are for "local" use.  The syntax of the auto list
       (if present) is "auto name, ... ;".  (The semicolon is optional.)  Each name is the name of  an  auto
       variable.  Arrays may be specified by using the same notation as used in parameters.  These variables
       have their values pushed onto a stack at the start of the function.  The variables are then  initial-ized initialized
       ized  to  zero  and used throughout the execution of the function.  At function exit, these variables
       are popped so that the original value (at the time of the  function  call)  of  these  variables  are
       restored.   The  parameters are really auto variables that are initialized to a value provided in the
       function call.  Auto variables are different than traditional local variables because if  function  A
       calls  function B, B may access function A's auto variables by just using the same name, unless func-tion function
       tion B has called them auto variables.  Due to the fact that auto variables and parameters are pushed
       onto a stack, bc supports recursive functions.

       The  function body is a list of bc statements.  Again, statements are separated by semicolons or new-lines. newlines.
       lines.  Return statements cause the termination of a function and the return of a value.   There  are
       two  versions  of the return statement.  The first form, "return", returns the value 0 to the calling
       expression.  The second form, "return ( expression )", computes  the  value  of  the  expression  and
       returns  that  value to the calling expression.  There is an implied "return (0)" at the end of every
       function.  This allows a function to terminate and return 0 without an explicit return statement.

       Functions also change the usage of the variable ibase.  All constants in the function  body  will  be
       converted  using  the  value  of  ibase  at  the time of the function call.  Changes of ibase will be
       ignored during the execution of the function except for the standard function read, which will always
       use the current value of ibase for conversion of numbers.

       As  an  extension, the format of the definition has been slightly relaxed.  The standard requires the
       opening brace be on the same line as the define keyword and all other  parts  must  be  on  following
       lines.   This  version  of bc will allow any number of newlines before and after the opening brace of
       the function.  For example, the following definitions are legal.
              define d (n) { return (2*n); }
              define d (n)
                { return (2*n); }

   MATH LIBRARY
       If bc is invoked with the -l option, a math library is preloaded and the default scale is set to  20.
       The math functions will calculate their results to the scale set at the time of their call.  The math
       library defines the following functions:

       s (x)  The sine of x, x is in radians.

       c (x)  The cosine of x, x is in radians.

       a (x)  The arctangent of x, arctangent returns radians.

       l (x)  The natural logarithm of x.

       e (x)  The exponential function of raising e to the value x.

       j (n,x)
              The bessel function of integer order n of x.

   EXAMPLES
       In /bin/sh,  the following will assign the value of "pi" to the shell variable pi.
               pi=$(echo "scale=10; 4*a(1)" | bc -l)

       The following is the definition of the exponential function used in the math library.  This  function
       is written in POSIX bc.
              scale = 20

              /* Uses the fact that e^x = (e^(x/2))^2
                 When x is small enough, we use the series:
                   e^x = 1 + x + x^2/2! + x^3/3! + ...
              */

              define e(x) {
                auto  a, d, e, f, i, m, v, z

                /* Check the sign of x. */
                if (x<0) {
                  m = 1
                  x = -x
                }

                /* Precondition x. */
                z = scale;
                scale = 4 + z + .44*x;
                while (x > 1) {
                  f += 1;
                  x /= 2;
                }

                /* Initialize the variables. */
                v = 1+x
                a = x
                d = 1

                for (i=2; 1; i++) {
                  e = (a *= x) / (d *= i)
                  if (e == 0) {
                    if (f>0) while (f--)  v = v*v;
                    scale = z
                    if (m) return (1/v);
                    return (v/1);
                  }
                  v += e
                }
              }

       The  following is code that uses the extended features of bc to implement a simple program for calcu-lating calculating
       lating checkbook balances.  This program is best kept in a file so that it can  be  used  many  times
       without having to retype it at every use.
              scale=2
              print "\nCheck book program!\n"
              print "  Remember, deposits are negative transactions.\n"
              print "  Exit by a 0 transaction.\n\n"

              print "Initial balance? "; bal = read()
              bal /= 1
              print "\n"
              while (1) {
                "current balance = "; bal
                "transaction? "; trans = read()
                if (trans == 0) break;
                bal -= trans
                bal /= 1
              }
              quit

       The following is the definition of the recursive factorial function.
              define f (x) {
                if (x <= 1) return (1);
                return (f(x-1) * x);
              }

   READLINE AND LIBEDIT OPTIONS
       GNU  bc  can be compiled (via a configure option) to use the GNU readline input editor library or the
       BSD libedit library.  This allows the user to do editing of lines before sending them to bc.  It also
       allows  for a history of previous lines typed.  When this option is selected, bc has one more special
       variable.  This special variable, history is the number of lines of history retained.  For  readline,
       a  value  of  -1  means that an unlimited number of history lines are retained.  Setting the value of
       history to a positive number restricts the number of history lines to the number given.  The value of
       0  disables the history feature.  The default value is 100. For more information, read the user manu-
       als for the GNU readline, history and BSD libedit libraries.  One can not enable  both  readline  and
       libedit at the same time.

   DIFFERENCES
       This  version of bc was implemented from the POSIX P1003.2/D11 draft and contains several differences
       and extensions relative to the draft and traditional implementations.  It is not implemented  in  the
       traditional  way  using  dc(1).   This  version is a single process which parses and runs a byte code
       translation of the program.  There is an "undocumented" option (-c) that causes the program to output
       the  byte  code  to  the standard output instead of running it.  It was mainly used for debugging the
       parser and preparing the math library.

       A major source of differences is extensions, where a feature is extended to  add  more  functionality
       and  additions,  where  new  features are added.  The following is the list of differences and exten-sions. extensions.
       sions.

       LANG   This version does not conform to the POSIX standard in the processing of the LANG  environment
              variable and all environment variables starting with LC_.

       names  Traditional  and  POSIX bc have single letter names for functions, variables and arrays.  They
              have been extended to be multi-character names that start with a letter and may  contain  let-ters, letters,
              ters, numbers and the underscore character.

       Strings
              Strings are not allowed to contain NUL characters.  POSIX says all characters must be included
              in strings.

       last   POSIX bc does not have a last variable.  Some implementations of bc use the period  (.)  in  a
              similar way.

       comparisons
              POSIX  bc  allows  comparisons  only  in the if statement, the while statement, and the second
              expression of the for statement.  Also, only one relational operation is allowed  in  each  of
              those statements.

       if statement, else clause
              POSIX bc does not have an else clause.

       for statement
              POSIX bc requires all expressions to be present in the for statement.

       &&, ||, !
              POSIX bc does not have the logical operators.

       read function
              POSIX bc does not have a read function.

       print statement
              POSIX bc does not have a print statement .

       continue statement
              POSIX bc does not have a continue statement.

       return statement
              POSIX bc requires parentheses around the return expression.

       array parameters
              POSIX  bc does not (currently) support array parameters in full.  The POSIX grammar allows for
              arrays in function definitions, but does not provide a method to specify an array as an actual
              parameter.  (This is most likely an oversight in the grammar.)  Traditional implementations of
              bc have only call by value array parameters.

       function format
              POSIX bc requires the opening brace on the same line as the  define  key  word  and  the  auto
              statement on the next line.

       =+, =-, =*, =/, =%, =^
              POSIX  bc does not require these "old style" assignment operators to be defined.  This version
              may allow these "old style" assignments.  Use the limits statement to  see  if  the  installed
              version supports them.  If it does support the "old style" assignment operators, the statement
              "a =- 1" will decrement a by 1 instead of setting a to the value -1.

       spaces in numbers
              Other implementations of bc allow spaces in numbers.  For example, "x=1 3"  would  assign  the
              value  13 to the variable x.  The same statement would cause a syntax error in this version of
              bc.

       errors and execution
              This implementation varies from other implementations in terms of what code will  be  executed
              when  syntax and other errors are found in the program.  If a syntax error is found in a func-tion function
              tion definition, error recovery tries to find the beginning of a  statement  and  continue  to
              parse  the  function.   Once a syntax error is found in the function, the function will not be
              callable and becomes undefined.  Syntax errors in the interactive execution code will  invali-date invalidate
              date  the  current  execution block.  The execution block is terminated by an end of line that
              appears after a complete sequence of statements.  For example,
              a = 1
              b = 2
       has two execution blocks and
              { a = 1
                b = 2 }
       has one execution block.  Any runtime error will terminate the execution  of  the  current  execution
       block.  A runtime warning will not terminate the current execution block.

       Interrupts
              During an interactive session, the SIGINT signal (usually generated by the control-C character
              from the terminal) will cause execution of the current execution block to be interrupted.   It
              will  display  a "runtime" error indicating which function was interrupted.  After all runtime
              structures have been cleaned up, a message will be printed to notify the user that bc is ready
              for more input.  All previously defined functions remain defined and the value of all non-auto
              variables are the value at the point of interruption.  All auto variables and function parame-ters parameters
              ters  are  removed  during the clean up process.  During a non-interactive session, the SIGINT
              signal will terminate the entire run of bc.

   LIMITS
       The following are the limits currently in place for this bc processor.  Some of them  may  have  been
       changed by an installation.  Use the limits statement to see the actual values.

       BC_BASE_MAX
              The maximum output base is currently set at 999.  The maximum input base is 16.

       BC_DIM_MAX
              This  is  currently an arbitrary limit of 65535 as distributed.  Your installation may be dif-ferent. different.
              ferent.

       BC_SCALE_MAX
              The number of digits after the decimal point is limited to INT_MAX digits.  Also,  the  number
              of digits before the decimal point is limited to INT_MAX digits.

       BC_STRING_MAX
              The limit on the number of characters in a string is INT_MAX characters.

       exponent
              The value of the exponent in the raise operation (^) is limited to LONG_MAX.

       variable names
              The  current limit on the number of unique names is 32767 for each of simple variables, arrays
              and functions.

ENVIRONMENT VARIABLES
       The following environment variables are processed by bc:

       POSIXLY_CORRECT
              This is the same as the -s option.

       BC_ENV_ARGS
              This is another mechanism to get arguments to bc.  The format is the same as the command  line
              arguments.   These  arguments are processed first, so any files listed in the environent argu-ments arguments
              ments are processed before any command line argument files.  This allows the user  to  set  up
              "standard"  options  and  files  to  be processed at every invocation of bc.  The files in the
              environment variables would typically contain function  definitions  for  functions  the  user
              wants defined every time bc is run.

       BC_LINE_LENGTH
              This  should  be  an integer specifing the number of characters in an output line for numbers.
              This includes the backslash and newline characters for long numbers.

DIAGNOSTICS
       If any file on the command line can not be opened, bc will report that the file  is  unavailable  and
       terminate.  Also, there are compile and run time diagnostics that should be self-explanatory.

BUGS
       Error recovery is not very good yet.

       Email  bug  reports  to  bug-bc@gnu.org.   Be sure to include the word ``bc'' somewhere in the ``Sub-ject:'' ``Subject:''
       ject:'' field.

AUTHOR
       Philip A. Nelson
       philnelson@acm.org

ACKNOWLEDGEMENTS
       The author would like to thank Steve Sommars (Steve.Sommars@att.com) for his extensive help in  test-ing testing
       ing the implementation.  Many great suggestions were given.  This is a much better product due to his
       involvement.



                                                      .                                                bc(1)

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