NAME

dc − desk calculator

SYNOPSIS

dc [ file ]

DESCRIPTION

Dc is an arbitrary precision arithmetic package.  Ordinarily it operates on decimal integers, but the user can specify an input base, output base, and a number of fractional digits to be maintained.  The overall structure of dc is a stacking (reverse Polish) calculator.  If an argument is given, input is taken from that file until its end, then from the standard input.  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.  It may be preceded by an underscore _ to input a negative number.  Numbers may contain decimal points. 

+ − / ∗ % ^
The top two values on the stack are manipulated as follows: added ( + ), subtracted ( − ), multiplied ( ∗ ), divided ( / ), remaindered ( % ), 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.

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

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

; : Used by bc for array operations. 

[ ... ] Puts the bracketed ASCII string onto the top of the stack. 

c All values on the stack are popped. 

d The top value on the stack is duplicated. 

f All values on the stack and in registers are printed. 

i The top value on the stack is popped and used as the number radix for further input. 

I Pushes the input base on the top of 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, division, and exponentiation.  The interaction of scale factor, input base, and output base will be reasonable if all are changed together. 

lx The value in register x is pushed on the stack.  The register x is not altered.  All registers start with zero value. 

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

o The top value on the stack is popped and used as the number radix for further output. 

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

p The top value on the stack is printed.  The top value remains unchanged. 

P Interprets the top of the stack as an ASCII string, removes it, and prints it. 

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

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

sx The top of the stack is popped and stored into a register named x, where x may be any character. 

Sx The x is treated as a stack and the value is pushed on it. 

v Replaces the top element on the stack by its square root.  Any existing fractional part of the argument is taken into account, but otherwise the scale factor is ignored. 

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

X Replaces the number on the top of the stack with its scale factor. 

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

z The stack level is pushed onto the stack. 

implied by the loop.  (To the extent that this allows, backward gotos will succeed on non-seekable inputs.)  Builtin commands are executed within the shell. If a builtin command occurs as any component of a pipeline except the last, then it is executed in a subshell.

alias

alias name

alias name wordlist
The first form prints all aliases. The second form prints the alias for name.  Z Replaces the number on the top of the stack with its length. 

EXAMPLE

An example which prints the first ten values of n! is

[la1+dsa∗pla10>y]sy
0sa1
lyx

SEE ALSO

R. Morris and L. Cherry, DC — An Interactive Desk Calculator, in volume III of the UNIX Programmer’s Manual. 
Bc(1), a preprocessor for dc, providing infix notation and a C-like syntax which imp

INTEGRATED SOLUTIONS 4.2 BSD  —  1 August 1985