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 in-
put 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 stan-
dard 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 (+), 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 reg-
ister 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 recur-
sion level is popped by two. If q is capitalized, the
top value on the stack is popped and the string execu-
tion 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.
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DC(I) 2/8/75 DC(I)
[ ... ]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 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 in-
teraction 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 (usual-
ly 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 nota-
tion 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.
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DC(I) 2/8/75 DC(I)
BUGS
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