Provided by: dc_1.07.1-2_amd64 bug

NAME

       dc - an arbitrary precision calculator

SYNOPSIS

       dc [-V] [--version] [-h] [--help]
          [-e scriptexpression] [--expression=scriptexpression]
          [-f scriptfile] [--file=scriptfile]
          [file ...]

DESCRIPTION

       dc is a reverse-polish desk calculator which supports unlimited precision arithmetic.  It also allows you
       to define and call macros.  Normally dc reads from the standard input; if any command arguments are given
       to  it,  they  are  filenames,  and  dc  reads and executes the contents of the files before reading from
       standard input.  All normal output is to standard output; all error output is to standard error.

       A reverse-polish calculator stores numbers on a stack.   Entering  a  number  pushes  it  on  the  stack.
       Arithmetic operations pop arguments off the stack and push the results.

       To  enter  a number in dc, type the digits (using upper case letters A through F as "digits" when working
       with input bases greater than ten),  with  an  optional  decimal  point.   Exponential  notation  is  not
       supported.   To  enter a negative number, begin the number with ``_''.  ``-'' cannot be used for this, as
       it is a binary operator for subtraction instead.  To enter two numbers in succession, separate them  with
       spaces or newlines.  These have no meaning as commands.

OPTIONS

       dc may be invoked with the following command-line options:

       -V

       --version
              Print out the version of dc that is being run and a copyright notice, then exit.

       -h

       --help Print  a  usage  message  briefly  summarizing  these  command-line  options and the bug-reporting
              address, then exit.

       -e script

       --expression=script
              Add the commands in script to the set of commands to be run while processing the input.

       -f script-file

       --file=script-file
              Add the commands contained in the file script-file  to  the  set  of  commands  to  be  run  while
              processing the input.

       If any command-line parameters remain after processing the above, these parameters are interpreted as the
       names of input files to be processed.  A file name of  -  refers  to  the  standard  input  stream.   The
       standard input will processed if no script files or expressions are specified.

Printing Commands

       p      Prints  the value on the top of the stack, without altering the stack.  A newline is printed after
              the value.

       n      Prints the value on the top of the stack, popping it off, and does not print a newline after.

       P      Pops off the value on top of the stack.  If it it  a  string,  it  is  simply  printed  without  a
              trailing  newline.   Otherwise  it  is  a number, and the integer portion of its absolute value is
              printed out as a "base (UCHAR_MAX+1)" byte stream.  Assuming that (UCHAR_MAX+1) is 256 (as  it  is
              on    most    machines    with    8-bit    bytes),    the    sequence    KSK0k1/_1Ss   [ls*]Sxd0>x
              [256~Ssd0<x]dsxxsx[q]Sq[Lsd0>qaPlxx] dsxxsx0sqLqsxLxLK+k  could  also  accomplish  this  function.
              (Much  of  the  complexity  of  the  above native-dc code is due to the ~ computing the characters
              backwards, and the desire to ensure that all registers wind up back in their original states.)

       f      Prints the entire contents of the stack without altering anything.  This is a good command to  use
              if you are lost or want to figure out what the effect of some command has been.

Arithmetic

       +      Pops  two  values off the stack, adds them, and pushes the result.  The precision of the result is
              determined only by the values of the arguments, and is enough to be exact.

       -      Pops two values, subtracts the first one popped from the second one popped, and pushes the result.

       *      Pops two values, multiplies them, and pushes the result.  The number of  fraction  digits  in  the
              result  depends  on  the  current  precision  value  and  the number of fraction digits in the two
              arguments.

       /      Pops two values, divides the second one popped from the first one popped, and pushes  the  result.
              The number of fraction digits is specified by the precision value.

       %      Pops  two  values,  computes the remainder of the division that the / command would do, and pushes
              that.  The value computed is the same as that computed by the sequence Sd dld/ Ld*- .

       ~      Pops two values, divides the second one popped from the first one popped.  The quotient is  pushed
              first,  and  the  remainder is pushed next.  The number of fraction digits used in the division is
              specified by the precision value.  (The sequence SdSn  lnld/  LnLd%  could  also  accomplish  this
              function, with slightly different error checking.)

       ^      Pops  two  values  and  exponentiates, using the first value popped as the exponent and the second
              popped as the base.  The fraction part of the exponent is ignored.  The precision value  specifies
              the number of fraction digits in the result.

       |      Pops  three  values  and computes a modular exponentiation.  The first value popped is used as the
              reduction modulus; this value must be a non-zero number, and should be  an  integer.   The  second
              popped  is used as the exponent; this value must be a non-negative number, and any fractional part
              of this exponent will be ignored.  The third value popped is the base  which  gets  exponentiated,
              which  should  be an integer.  For small integers this is like the sequence Sm^Lm%, but, unlike ^,
              this command will work with arbitrarily large exponents.

       v      Pops one value, computes its square root, and pushes that.  The maximum of the precision value and
              the precision of the argument is used to determine the number of fraction digits in the result.

       Most arithmetic operations are affected by the ``precision value'', which you can set with the k command.
       The default precision value is zero, which means that all arithmetic except for addition and  subtraction
       produces integer results.

Stack Control

       c      Clears the stack, rendering it empty.

       d      Duplicates the value on the top of the stack, pushing another copy of it.  Thus, ``4d*p'' computes
              4 squared and prints it.

       r      Reverses the order of (swaps) the top two values on the stack.  (This  can  also  be  accomplished
              with the sequence SaSbLaLb.)

       R      Pops  the  top-of-stack as an integer n.  Cyclically rotates the top n items on the updated stack.
              If n is positive, then the rotation direction will make the topmost element the  second-from  top;
              if  n  is negative, then the rotation will make the topmost element the n-th element from the top.
              If the stack depth is less  than  n,  then  the  entire  stack  is  rotated  (in  the  appropriate
              direction), without any error being reported.

Registers

       dc provides at least 256 memory registers, each named by a single character.  You can store a number or a
       string in a register and retrieve it later.

       sr     Pop the value off the top of the stack and store it into register r.

       lr     Copy the value in register r and push it onto the stack.  The value 0 is retrieved if the register
              is uninitialized.  This does not alter the contents of r.

       Each  register  also  contains  its  own  stack.  The current register value is the top of the register's
       stack.

       Sr     Pop the value off the top of the (main) stack and push it onto  the  stack  of  register  r.   The
              previous value of the register becomes inaccessible.

       Lr     Pop  the  value  off  the top of register r's stack and push it onto the main stack.  The previous
              value in register r's stack, if any, is now accessible via the lr command.

Parameters

       dc has three parameters that control its operation: the precision, the input radix, and the output radix.
       The  precision  specifies  the  number  of  fraction  digits  to  keep  in  the result of most arithmetic
       operations.  The input radix controls the interpretation of numbers typed in; all numbers  typed  in  use
       this radix.  The output radix is used for printing numbers.

       The  input  and output radices are separate parameters; you can make them unequal, which can be useful or
       confusing.  The input radix must be between 2 and 16 inclusive.  The output radix must  be  at  least  2.
       The precision must be zero or greater.  The precision is always measured in decimal digits, regardless of
       the current input or output radix.

       i      Pops the value off the top of the stack and uses it to set the input radix.

       o      Pops the value off the top of the stack and uses it to set the output radix.

       k      Pops the value off the top of the stack and uses it to set the precision.

       I      Pushes the current input radix on the stack.

       O      Pushes the current output radix on the stack.

       K      Pushes the current precision on the stack.

Strings

       dc has a limited ability to operate on strings as well as on numbers; the only things  you  can  do  with
       strings  are  print  them  and  execute  them  as macros (which means that the contents of the string are
       processed as dc commands).  All registers and the stack can hold strings, and dc always knows whether any
       given  object  is  a  string  or a number.  Some commands such as arithmetic operations demand numbers as
       arguments and print errors if given strings.  Other commands can accept either a number or a string;  for
       example, the p command can accept either and prints the object according to its type.

       [characters]
              Makes  a  string containing characters (contained between balanced [ and ] characters), and pushes
              it on the stack.  For example, [foo]P prints the characters foo (with no newline).

       a      The top-of-stack is popped.  If it was a number,  then  the  low-order  byte  of  this  number  is
              converted  into  a string and pushed onto the stack.  Otherwise the top-of-stack was a string, and
              the first character of that string is pushed back.

       x      Pops a value off the stack and executes it as a macro.  Normally it should be a string; if it is a
              number,  it  is simply pushed back onto the stack.  For example, [1p]x executes the macro 1p which
              pushes 1 on the stack and prints 1 on a separate line.

       Macros are most often stored in registers; [1p]sa stores a macro to print 1  into  register  a,  and  lax
       invokes this macro.

       >r     Pops  two values off the stack and compares them assuming they are numbers, executing the contents
              of register r as a macro if the original  top-of-stack  is  greater.   Thus,  1  2>a  will  invoke
              register a's contents and 2 1>a will not.

       !>r    Similar but invokes the macro if the original top-of-stack is not greater than (less than or equal
              to) what was the second-to-top.

       <r     Similar but invokes the macro if the original top-of-stack is less.

       !<r    Similar but invokes the macro if the original top-of-stack is not less than (greater than or equal
              to) what was the second-to-top.

       =r     Similar but invokes the macro if the two numbers popped are equal.

       !=r    Similar but invokes the macro if the two numbers popped are not equal.

       ?      Reads a line from the terminal and executes it.  This command allows a macro to request input from
              the user.

       q      exits from a macro and also from the macro which invoked it.  If called from  the  top  level,  or
              from a macro which was called directly from the top level, the q command will cause dc to exit.

       Q      Pops  a  value  off  the  stack  and uses it as a count of levels of macro execution to be exited.
              Thus, 3Q exits three levels.  The Q command will never cause dc to exit.

Status Inquiry

       Z      Pops a value off the stack, calculates  the  number  of  decimal  digits  it  has  (or  number  of
              characters,  if  it  is  a  string) and pushes that number.  The digit count for a number does not
              include any leading zeros, even if those appear to the right of the radix point.

       X      Pops a value off the stack, calculates the number of fraction  digits  it  has,  and  pushes  that
              number.  For a string, the value pushed is 0.

       z      Pushes  the  current stack depth: the number of objects on the stack before the execution of the z
              command.

Miscellaneous

       !      Will run the rest of the line as a system command.  Note that  parsing  of  the  !<,  !=,  and  !>
              commands  take  precedence, so if you want to run a command starting with <, =, or > you will need
              to add a space after the !.

       #      Will interpret the rest of the line as a comment.

       :r     Will pop the top two values off of the stack.  The old second-to-top value will be stored  in  the
              array r, indexed by the old top-of-stack value.

       ;r     Pops the top-of-stack and uses it as an index into the array r.  The selected value is then pushed
              onto the stack.

       Note that each stacked instance of a register has its own array associated with it.  Thus 1 0:a 0Sa 2 0:a
       La 0;ap will print 1, because the 2 was stored in an instance of 0:a that was later popped.

FILES

       ~/.dcrc        The commands in this file will be executed when dc is first run.

BUGS

       Email bug reports to bug-dc@gnu.org.