OSF

NAME

dc − Provides an interactive desk calculator for arbitrary precision integer arithmetic

SYNOPSIS

dc

DESCRIPTION

The dc command is an arbitrary precision arithmetic calculator.  dc takes its input from file or standard input until it reads an End-of-File character.  It writes to standard output. 

dc operates on integers by default, but you can specify an input base, output base, and a number of fractional digits to be maintained.  dc is structured overall as a stacking, reverse Polish calculator. 

The bc command is a preprocessor for dc.  It provides infix notation and a syntax similar to the C language, which implements functions and reasonable control structures for programs. 

SUBCOMMANDS

numberPushes the specified value onto the stack.  number is an unbroken string of the digits 0 to 9.  To specify a negative number, precede it with _ (underscore).  A number can contain a decimal point. 

+ - / ∗ % ^
Adds (+), subtracts (-), multiplies (∗), divides (/), remainders (%), or exponentiates (^) the top two values on the stack.  dc pops the top two entries off the stack and pushes the result on the stack in their place. 

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

?Executes a line of input from standard input. 

cCleans the stack: dc pops all values on the stack. 

dDuplicates the top value on the stack. 

fDisplays all values on the stack. 

iPops the top value on the stack and uses that value as the number radix for further input. 

IPushes the input base on the top of the stack. 

kPops the top of the stack, and uses that value as a nonnegative scale factor.  The appropriate number of places is displayed on output and is maintained during multiplication, division, and exponentiation.  The interaction of scale factor, input base, and output base is reasonable if all are changed together. 

lxPushes the value in register x on the stack.  The register x is not changed.  All registers start with zero value. 

LxTreats x as a stack and pops its top value onto the main stack. 

oPops the top value on the stack and uses that value as the number radix for further output. 

OPushes the output base on the top of the stack. 

pPrints the top value on the stack.  The top value remains unchanged. 

PInterprets the top value on the stack as an ASCII string, prints it, and removes it. 

qExits the program.  If dc is executing a string, it pops the recursion level by two. 

QPops the top  value on the stack and the string execution level by that value. 

sxPops the top of the stack and stores it in a register named x, where x can be any character. 

vReplaces 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. 

SxTreats x as a stack.  It pops the top of the main stack and pushes that value onto stack x. 

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

XReplaces the number on the top of the stack with its scale factor. 

zPushes the number of elements in the stack onto the stack. 

ZReplaces the top number in the stack with the number of digits in that number. 

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

<x

>x

=xPops the top two elements of the stack and compares them.  Register x is executed if the stated relationship is TRUE. 

;:dc uses these characters for array operations. 

EXAMPLES

     1.To use dc as a calculator proceed as follows: Enter:

1 4 / p

The system responds as follows:

0

Enter:

1 k  [ Keep 1 decimal place]s.
1 4 / p

The system responds as follows:

0.2

Enter:

3 k  [ Keep 3 decimal places]s.
1 4 / p

The system responds as follows:

0.250

Enter:

16 63 5 / + p

The system responds as follows:

28.600

Enter:

16 63 5 + / p

The system responds as follows:

0.235

You can type the comments (enclosed in brackets), but they are provided only for your information. When you enter dc expressions directly from the keyboard, press the End-of-File key sequence to end the dc session and return to the shell command line. 

     2.To load and run a dc program file, proceed as follows: Enter:

dc prog.dc
5 lf x p  [  5 factorial ]s.

The system responds as follows:

120

Enter:

10 lf x p  [ 10 factorial ]s.

The system responds as follows:

3628800

This interprets the dc program saved in prog.dc, then reads from standard input.  The lf x evaluates the function stored in register f, which could be defined in the program file prog.dc as:

[ f: compute the factorial of n ]s.
 [(n = the top of the stack) ]s.
 [ If 1>n do b;  If 1<n do r ]s.
[d 1 >b d 1 <r] sf
 [ Return f(n) = 1]s.
[d - 1 +] sb
 [ Return f(n) = n ∗ f(n-1)  ]s.
[d 1 - lf x ∗] sr

You can create dc program files with a text editor, or with the -c (compile) flag of the bc command.  When you enter dc expressions directly from the keyboard, press the End-of-File key sequence to end the dc session and return to the shell command line. 

RELATED INFORMATION

Commands:  bc(1). 

OSF/1 User’s Guide.