# 32v 1m dc

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DC(1) UNIX Programmer's Manual DC(1)

## Contents

## NAME

dc - desk calculator

## SYNOPSIS

dc [ file ]

## DESCRIPTION

_D_c is an arbitrary precision arithmetic package. Ordinarily it operates on decimal integers, but one may specify an input base, output base, and a number of fractional digits to be maintained. The overall structure of _d_c is a stacking (reverse Polish) calculator. If an argument is given, input is taken from that file until its end, then from the stan- dard 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 added (+), sub- tracted (-), 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.

s_x The top of the stack is popped and stored into a register named _x, where _x may be any character. If the s is capitalized, _x is treated as a stack and the value is pushed on it.

l_x The value in register _x is pushed on the stack. The register _x is not altered. All registers start with zero value. If the l is capitalized, register _x is treated as a stack and its top value is popped onto the main stack.

d The top value on the stack is duplicated.

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.

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

q exits the program. If executing a string, the recur- sion level is popped by two. If q is capitalized, the top value on the stack is popped and the string execu- tion level is popped by that value.

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.

[ ... ] puts the bracketed ascii string onto the top of the stack.

<_x >_x =_x The top two elements of the stack are popped and com- pared. Register _x is executed if they obey the stated relation.

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.

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

c All values on the stack are popped.

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.

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.

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.

z The stack level is pushed onto the stack.

Z replaces the number on the top of the stack with its length.

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

; : are used by _b_c for array operations.

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

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

## SEE ALSO

bc(1), which is a preprocessor for _d_c providing infix nota- tion and a C-like syntax which implements functions and rea- sonable control structures for programs.

## DIAGNOSTICS

`x is unimplemented' where x is an octal number. `stack empty' for not enough elements on the stack to do what was asked. `Out of space' when the free list is exhausted (too many digits). `Out of headers' for too many numbers being kept around. `Out of pushdown' for too many items on the stack. `Nesting Depth' for too many levels of nested execution.