DC(1)DC(1)NAMEdc - desk calculator
SYNOPSISdc [ file ]
DESCRIPTION
Dc is an arbitrary precision arithmetic package. Ordinarily it oper‐
ates 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 dc is a stacking (reverse Polish) calculator. If an argu‐
ment 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 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.
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 and in registers are printed.
q exits the program. If executing a string, the recursion level is
popped by two. If q is capitalized, 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 fac‐
tor.
[ ... ]
puts the bracketed ascii string onto the top of the stack.
<x >x =x
The top two elements of the stack are popped and compared. Reg‐
ister 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, divi‐
sion, 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 (usually the ter‐
minal) and executed.
; : are used by bc for array operations.
An example which prints the first ten values of n! is
[la1+dsa*pla10>y]sy
0sa1
lyx
SEE ALSObc(1), which is a preprocessor for dc providing infix notation and a C-
like syntax which implements functions and reasonable control struc‐
tures 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.
DC(1)
