DC(I) 2/8/75 DC(I)
NAME
dc - desk calculator
SYNOPSIS
dc [ file ]
DESCRIPTION
Dc 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 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 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.
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.
[ ... ]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.
o The top value on the stack is popped and used as the
number radix for further output.
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.
? A line of input is taken from the input source
(usually the console) and executed.
An example which prints the first ten values of n! is
[la1+dsa*pla10>y]sy
0sa1
lyx
SEE ALSO
bc (I), which is a preprocessor for dc providing infix
notation and a C-like syntax which implements functions and
reasonable control structures for programs.
DIAGNOSTICS
(x) ? for unrecognized character x.
(x) ? for not enough elements on the stack to do what was
asked by command x.
`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.
BUGS