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 inter-
 active 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 doc-
 ument describes the language accepted by this processor. Extensions
 will be identified 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 pre-
 cision numbers. This precision is both in the integer part and the
 fractional part. All numbers are represented internally in decimal and
 all computation is done in decimal. (This version truncates results
 from divide and multiply operations.) There are two attributes of num-
 bers, the length and the scale. The length is the total number of sig-
 nificant 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 conversion 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 anywhere and appear as a single space in the
 input. (This causes comments to delimit other input items. For exam-
 ple, a comment can not be found in the middle of a variable name.)
 Comments include any newlines (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" program. 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 capitals. Lower case let-
 ters 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 performed and in many cases, the value of the variable scale.
 Legal values of the variable scale are 0 to the maximum number repre-
 sentable 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 incremented 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 expres-
 sions.
 expr / expr
 The result of the expression is the quotient of the two expres-
 sions. 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 com-
 puted in the following way. To compute a%b, first a/b is com-
 puted 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 generated 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 expo-
 nent and the maximum of scale and the scale of the first expres-
 sion. (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 evaluated 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 state-
 ments 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 operators
 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 opera-
 tors to have some unusual behavior when used with assignment expres-
 sions. 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 functions
 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 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 con-
 version base.
 scale ( expression )
 The value of the scale function is the number of digits after
 the decimal point in the expression.
 sqrt ( expression )
 The value of the sqrt function is the square root of the expres-
 sion. If the expression is negative, a run time error is gener-
 ated.
 STATEMENTS
 Statements (as in most algebraic languages) provide the sequencing of
 expression evaluation. In bc statements are executed "as soon as pos-
 sible." Execution happens when a newline in encountered and there is
 one or more complete statements. Due to this immediate execution, new-
 lines are very important 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 by semicolons and newlines. The following is a list of bc state-
 ments 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 out-
 put. 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 printing the numbers
 where each higher base digit is printed as a base 10 number.
 The multi-character 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 preci-
 sion, 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 num-
 ber 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 dou-
 ble 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 sepa-
 rated by commas. Each string or expression is printed in the
 order of the list. No terminating newline is printed. Expres-
 sions 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 charac-
 ters start with the backslash character (\). The special char-
 acters 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 execution.
 if ( expression ) statement1 [else statement2]
 The if statement evaluates the expression and executes state-
 ment1 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 expres-
 sion is non-zero. It evaluates the expression before each exe-
 cution 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 evalu-
 ated before each execution of the statement. If it is non-zero,
 the statement is evaluated. If it is zero, the loop is termi-
 nated. After each execution of the statement, expression3 is
 evaluated before the reevaluation of expression2. If expres-
 sion1 or expression3 are missing, nothing is evaluated at the
 point they would be evaluated. 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 statement.
 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 func-
 tions.)
 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 exe-
 cuted 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 defi-
 nition, zero or more parameters are defined by listing their names sep-
 arated by commas. Numbers are only call by value parameters. Arrays
 are only call by variable. Arrays are specified in the parameter defi-
 nition by the notation "name[]". In the function call, actual parame-
 ters 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 defini-
 tions are dynamic, parameter numbers and types are checked when a func-
 tion is called. Any mismatch in number or types of parameters will
 cause a runtime 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 vari-
 able. 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 initialized 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 function 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 newlines. Return statements cause the ter-
 mination of a function and the return of a value. There are two ver-
 sions of the return statement. The first form, "return", returns the
 value 0 to the calling expression. The second form, "return ( expres-
 sion )", 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 with-
 out 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 defini-
 tions 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 imple-
 ment a simple program for calculating 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 num-
 ber 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 fea-
 ture. The default value is 100. For more information, read the user
 manuals 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 "undocu-
 mented" 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 extensions.
 LANG This version does not conform to the POSIX standard in the pro-
 cessing 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-char-
 acter names that start with a letter and may contain letters,
 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" assign-
 ments. 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 exam-
 ple, "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 function
 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 interac-
 tive execution code will invalidate 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 execu-
 tion of the current execution block. A runtime warning will not termi-
 nate the current execution block.
 Interrupts
 During an interactive session, the SIGINT signal (usually gener-
 ated 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 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 different.
 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 arguments
 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 environ-
 ment 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 new-
 line 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 ``Subject:'' 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 testing the implementation. Many great sug-
 gestions were given. This is a much better product due to his involve-
 ment.
 . bc(1)