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DC(1)			FreeBSD	General	Commands Manual			 DC(1)

NAME
     dc	-- desk	calculator

SYNOPSIS
     dc	[-hxV] [-e expression] [-f filename] [filename]

DESCRIPTION
     dc	is an arbitrary	precision arithmetic package.  The overall structure
     of	dc is a	stacking (reverse Polish) calculator i.e. numbers are stored
     on	a stack.  Adding a number pushes it onto the stack.  Arithmetic	opera-
     tions pop arguments off the stack and push	the results.  See also the
     bc(1) utility, which is a preprocessor for	dc providing infix notation
     and a C-like syntax which implements functions and	reasonable control
     structures	for programs.  The options are as follows:

     -e	expr, --expression expr
	     Evaluate expression.  If multiple -e options are specified, they
	     will be processed in the order given.  If no filename argument is
	     given, execution will stop	after processing the expressions given
	     on	the command line, otherwise processing will continue with the
	     contents of filename.

     -f	filename, --file filename
	     Process the content of the	given file before further calculations
	     are done.	If multiple -f options are specified, they will	be
	     processed in the order given.

     -h, --help
	     Print short usage info.

     -V, --version
	     Print version info.

     -x	     Enable extended register mode.  This mode is used by bc(1)	to
	     allow more	than 256 registers.  See Registers for a more detailed
	     description.

     Ordinarily, dc operates on	decimal	integers, but one may specify an input
     base, output base,	and a number of	fractional digits (scale) to be	main-
     tained.  If an argument is	given, input is	taken from that	file until its
     end, then from the	standard input.	 Whitespace is ignored,	except where
     it	signals	the end	of a number, end of a line or when a register name is
     expected.	The following constructions are	recognized:

     number  The value of the number is	pushed on the stack.  A	number is an
	     unbroken string of	the digits 0-9 and letters A-F.	 It may	be
	     preceded by an underscore (`_') to	input a	negative number.  A
	     number may	contain	a single decimal point.	 A number may also
	     contain the characters A-F, with the values 10-15.

     + - / * % ~ ^
	     The top two values	on the stack are added (+), subtracted (-),
	     multiplied	(*), divided (/), remaindered (%), divided and remain-
	     dered (~),	or exponentiated (^).  The two entries are popped off
	     the stack;	the result is pushed on	the stack in their place.  Any
	     fractional	part of	an exponent is ignored.

	     For addition and subtraction, the scale of	the result is the max-
	     imum of scales of the operands.  For division the scale of	the
	     result is defined by the scale set	by the k operation.  For mul-
	     tiplication, the scale is defined by the expression
	     min(a+b,max(a,b,scale)), where a and b are	the scales of the op-
	     erands, and scale is the scale defined by the k operation.	 For
	     exponentiation with a non-negative	exponent, the scale of the
	     result is min(a*b,max(scale,a)), where a is the scale of the
	     base, and b is the	value of the exponent.	If the exponent	is
	     negative, the scale of the	result is the scale defined by the k
	     operation.

	     In	the case of the	division and modulus operator (~), the resul-
	     tant quotient is pushed first followed by the remainder.  This is
	     a shorthand for the sequence:
		   x y / x y %
	     The division and modulus operator is a non-portable extension.

     a	     Pop the top value from the	stack.	If that	value is a number,
	     compute the integer part of the number modulo 256.	 If the	result
	     is	zero, push an empty string.  Otherwise push a one character
	     string by interpreting the	computed value as an ASCII character.

	     If	the top	value is a string, push	a string containing the	first
	     character of the original string.	If the original	string is
	     empty, an empty string is pushed back.  The a operator is a non-
	     portable extension.

     c	     All values	on the stack are popped.

     d	     The top value on the stack	is duplicated.

     f	     All values	on the stack are printed, separated by newlines.

     G	     The top two numbers are popped from the stack and compared.  A
	     one is pushed if the top of the stack is equal to the second num-
	     ber on the	stack.	A zero is pushed otherwise.  This is a non-
	     portable extension.

     I	     Pushes the	input base on the top of the stack.

     i	     The top value on the stack	is popped and used as the base for
	     further input.  The initial input base is 10.

     J	     Pop the top value from the	stack.	The recursion level is popped
	     by	that value and,	following that,	the input is skipped until the
	     first occurrence of the M operator.  The J	operator is a non-por-
	     table extension, used by the bc(1)	command.

     K	     The current scale factor is pushed	onto the stack.

     k	     The top of	the stack is popped, and that value is used as a non-
	     negative scale factor: the	appropriate number of places are
	     printed on	output,	and maintained during multiplication, divi-
	     sion, and exponentiation.	The interaction	of scale factor, input
	     base, and output base will	be reasonable if all are changed
	     together.

     Lx	     Register x	is treated as a	stack and its top value	is popped onto
	     the main stack.

     lx	     The value in register x is	pushed on the stack.  The register x
	     is	not altered.  Initially, all registers contain the value zero.

     M	     Mark used by the J	operator.  The M operator is a non-portable
	     extensions, used by the bc(1) command.

     N	     The top of	the stack is replaced by one if	the top	of the stack
	     is	equal to zero.	If the top of the stack	is unequal to zero, it
	     is	replaced by zero.  This	is a non-portable extension.

     n	     The top value on the stack	is popped and printed without a	new-
	     line.  This is a non-portable extension.

     O	     Pushes the	output base on the top of the stack.

     o	     The top value on the stack	is popped and used as the base for
	     further output.  The initial output base is 10.

     P	     The top of	the stack is popped.  If the top of the	stack is a
	     string, it	is printed without a trailing newline.	If the top of
	     the stack is a number, it is interpreted as a base	256 number,
	     and each digit of this base 256 number is printed as an ASCII
	     character,	without	a trailing newline.

     p	     The top value on the stack	is printed with	a trailing newline.
	     The top value remains unchanged.

     Q	     The top value on the stack	is popped and the string execution
	     level is popped by	that value.

     q	     Exits the program.	 If executing a	string,	the recursion level is
	     popped by two.

     R	     The top of	the stack is removed (popped).	This is	a non-portable
	     extension.

     r	     The top two values	on the stack are reversed (swapped).  This is
	     a non-portable extension.

     Sx	     Register x	is treated as a	stack.	The top	value of the main
	     stack is popped and pushed	on it.

     sx	     The top of	the stack is popped and	stored into a register named
	     x.

     v	     Replaces the top element on the stack by its square root.	The
	     scale of the result is the	maximum	of the scale of	the argument
	     and the current value of scale.

     X	     Replaces the number on the	top of the stack with its scale	fac-
	     tor.  If the top of the stack is a	string,	replace	it with	the
	     integer 0.

     x	     Treats the	top element of the stack as a character	string and
	     executes it as a string of	dc commands.

     Z	     Replaces the number on the	top of the stack with its length.  The
	     length of a string	is its number of characters.  The length of a
	     number is its number of digits, not counting the minus sign and
	     decimal point.

     z	     The stack level is	pushed onto the	stack.

     [...]   Puts the bracketed	ASCII string onto the top of the stack.	 If
	     the string	includes brackets, these must be properly balanced.
	     The backslash character (`\') may be used as an escape character,
	     making it possible	to include unbalanced brackets in strings.  To
	     include a backslash in a string, use a double backslash.

     <x	>x =x !<x !>x !=x
	     The top two elements of the stack are popped and compared.	 Reg-
	     ister x is	executed if they obey the stated relation.

     <xey >xey =xey !<xey !>xey	!=xey
	     These operations are variants of the comparison operations	above.
	     The first register	name is	followed by the	letter `e' and another
	     register name.  Register x	will be	executed if the	relation is
	     true, and register	y will be executed if the relation is false.
	     This is a non-portable extension.

     (	     The top two numbers are popped from the stack and compared.  A
	     one is pushed if the top of the stack is less than	the second
	     number on the stack.  A zero is pushed otherwise.	This is	a non-
	     portable extension.

     {	     The top two numbers are popped from the stack and compared.  A
	     one is pushed if the top of stack is less than or equal to	the
	     second number on the stack.  A zero is pushed otherwise.  This is
	     a non-portable extension.

     !	     Interprets	the rest of the	line as	a UNIX command.

     ?	     A line of input is	taken from the input source (usually the ter-
	     minal) and	executed.

     :r	     Pop two values from the stack.  The second	value on the stack is
	     stored into the array r indexed by	the top	of stack.

     ;r	     Pop a value from the stack.  The value is used as an index	into
	     register r.  The value in this register is	pushed onto the	stack.

	     Array elements initially have the value zero.  Each level of a
	     stacked register has its own array	associated with	it.  The com-
	     mand sequence

		   [first] 0:a [dummy] Sa [second] 0:a 0;a p La	0;a p

	     will print

		   second
		   first

	     since the string `second' is written in an	array that is later
	     popped, to	reveal the array that stored `first'.

     #	     Skip the rest of the line.	 This is a non-portable	extension.

   Registers
     Registers have a single character name x, where x may be any character,
     including space, tab or any other special character.  If extended regis-
     ter mode is enabled using the -x option and the register identifier x has
     the value 255, the	next two characters are	interpreted as a two-byte reg-
     ister index.  The set of standard single character	registers and the set
     of	extended registers do not overlap.  Extended register mode is a	non-
     portable extension.

EXAMPLES
     An	example	which prints the first ten values of n!:

	   [la1+dsa*pla10>y]sy
	   0sa1
	   lyx

     Independent of the	current	input base, the	command

	   Ai

     will reset	the input base to decimal 10.

DIAGNOSTICS
     %c	(0%o) is unimplemented	an undefined operation was called.

     stack empty  for not enough elements on the stack to do what was asked.

     stack register '%c' (0%o) is empty	 for an	L operation from a stack reg-
     ister that	is empty.

     Runtime warning: non-zero scale in	exponent  for a	fractional part	of an
     exponent that is being ignored.

     divide by zero  for trying	to divide by zero.

     remainder by zero	for trying to take a remainder by zero.

     square root of negative number  for trying	to take	the square root	of a
     negative number.

     index too big  for	an array index that is larger than 2048.

     negative index  for a negative array index.

     input base	must be	a number between 2 and 16  for trying to set an	ille-
     gal input base.

     output base must be a number greater than 1  for trying to	set an illegal
     output base.

     scale must	be a nonnegative number	 for trying to set a negative or zero
     scale.

     scale too large  for trying to set	a scale	that is	too large.  A scale
     must be representable as a	32-bit unsigned	number.

     Q command argument	exceeded string	execution depth	 for trying to pop the
     recursion level more than the current recursion level.

     Q command requires	a number >= 1  for trying to pop an illegal number of
     recursion levels.

     recursion too deep	 for too many levels of	nested execution.

     The recursion level is increased by one if	the x or ? operation or	one of
     the compare operations resulting in the execution of register is exe-
     cuted.  As	an exception, the recursion level is not increased if the
     operation is executed as the last command of a string.  For example, the
     commands

	   [lax]sa
	   1 lax

     will execute an endless loop, while the commands

	   [laxp]sa
	   1 lax

     will terminate because of a too deep recursion level.

     J command argument	exceeded string	execution depth	 for trying to pop the
     recursion level more than the current recursion level.

     mark not found  for a failed scan for an occurrence of the	M operator.

SEE ALSO
     bc(1)

     L.	L. Cherry, R. Morris "DC - An Interactive Desk Calculator"
     /usr/share/doc/usd/05.dc/.

STANDARDS
     The arithmetic operations of the dc utility are expected to conform to
     the definition listed in the bc(1)	section	of the IEEE Std	1003.2
     (``POSIX.2'') specification.

HISTORY
     The dc command first appeared in Version 6	AT&T UNIX.  A complete rewrite
     of	the dc command using the bn(3) big number routines first appeared in
     OpenBSD 3.5.

AUTHORS
     The original version of the dc command was	written	by Robert Morris and
     Lorinda Cherry.  The current version of the dc utility was	written	by
     Otto Moerbeek.

FreeBSD	9.2		       January 22, 2010			   FreeBSD 9.2

NAME | SYNOPSIS | DESCRIPTION | EXAMPLES | DIAGNOSTICS | SEE ALSO | STANDARDS | HISTORY | AUTHORS

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