DC(1) INTERACTIVE UNIX System DC(1)
NAME
dc - desk calculator
SYNOPSIS
dc [ file ]
DESCRIPTION
The dc command 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 frac-
tional digits to be maintained. [See bc(1), a preprocessor
for dc that provides infix notation and a C-like syntax that
implements functions. bc also provides reasonable control
structures for programs.] 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 nega-
tive 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.
sx 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.
lx 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 are printed.
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DC(1) INTERACTIVE UNIX System DC(1)
q Exits the program. If executing a string, the recur-
sion level is popped by two.
Q Exits the program. The top value on the stack is
popped and the string execution 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 evaluated 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 system com-
mand.
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 out-
put 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
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length.
? A line of input is taken from the input source (usu-
ally the terminal) and executed.
; : are used by bc(1) for array operations.
EXAMPLE
This example prints the first ten values of n!:
[la1+dsa*pla10>y]sy
0sa1
lyx
SEE ALSO
bc(1).
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.
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