dc(1) General Commands Manual dc(1)
dc - desktop calculator
The command is an arbitrary precision arithmetic package. Ordinarily it operates on decimal integers, but you can specify an input base,
output base, and a number of fractional digits to be maintained. The overall structure of 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 recog-
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 under-
score _ 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
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.
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 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 compared. 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. When the base (number radix) is re-set, all
subsequent numbers are interpreted in the new base.
For example, if the command is issued twice, first to set the base to base 2, then to reset it back to base 10, the new base value
must be given in the base originally set (that is, `2 i' will set the base to base 2, after which `1010 i' will set it back to base
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 (usually the terminal) and executed.
; : Used by for array operations.
An example which prints the first ten values of n! is the following:
"x is unimplemented"
x is an octal number.
Not enough elements on the stack to do what was asked.
"Out of space"
The free list is exhausted (too many digits).
"Out of headers"
Too many numbers being kept around.
"Out of pushdown"
Too many items on the stack.
Too many levels of nested execution.