dc.1 - 9base - revived minimalist port of Plan 9 userland to Unix
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dc.1 (4834B)
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1 .TH DC 1
2 .SH NAME
3 dc \- desk calculator
4 .SH SYNOPSIS
5 .B dc
6 [
7 .I file
8 ]
9 .SH DESCRIPTION
10 .I Dc
11 is an arbitrary precision desk calculator.
12 Ordinarily it operates on decimal integers,
13 but one may specify an input base, output base,
14 and a number of fractional digits to be maintained.
15 The overall structure of
16 .I dc
17 is
18 a stacking (reverse Polish) calculator.
19 If an argument is given,
20 input is taken from that file until its end,
21 then from the standard input.
22 The following constructions are recognized:
23 .TP
24 number
25 The value of the number is pushed on the stack.
26 A number is an unbroken string of the digits
27 .B 0-9A-F
28 or
29 .BR 0-9a-f .
30 A hexadecimal number beginning with a lower case
31 letter must be preceded by a zero to distinguish it
32 from the command associated with the letter.
33 It may be preceded by an underscore
34 .B _
35 to input a
36 negative number.
37 Numbers may contain decimal points.
38 .TP
39 .L
40 + - / * % ^
41 Add
42 .LR + ,
43 subtract
44 .LR - ,
45 multiply
46 .LR * ,
47 divide
48 .LR / ,
49 remainder
50 .LR % ,
51 or exponentiate
52 .L ^
53 the top two values on the stack.
54 The two entries are popped off the stack;
55 the result is pushed on the stack in their place.
56 Any fractional part of an exponent is ignored.
57 .TP
58 .BI s x
59 .br
60 .ns
61 .TP
62 .BI S x
63 Pop the top of the stack and store into
64 a register named
65 .IR x ,
66 where
67 .I x
68 may be any character.
69 Under operation
70 .B S
71 register
72 .I x
73 is treated as a stack and the value is pushed on it.
74 .TP
75 .BI l x
76 .br
77 .ns
78 .TP
79 .BI L x
80 Push the value in register
81 .I x
82 onto the stack.
83 The register
84 .I x
85 is not altered.
86 All registers start with zero value.
87 Under operation
88 .B L
89 register
90 .I x
91 is treated as a stack and its top value is popped onto the main stack.
92 .TP
93 .B d
94 Duplicate the
95 top value on the stack.
96 .TP
97 .B p
98 Print the top value on the stack.
99 The top value remains unchanged.
100 .B P
101 interprets the top of the stack as an
102 text
103 string,
104 removes it, and prints it.
105 .TP
106 .B f
107 Print the values on the stack.
108 .TP
109 .B q
110 .br
111 .ns
112 .TP
113 .B Q
114 Exit the program.
115 If executing a string, the recursion level is
116 popped by two.
117 Under operation
118 .B Q
119 the top value on the stack is popped and the string execution level is popped
120 by that value.
121 .TP
122 .B x
123 Treat the top element of the stack as a character string
124 and execute it as a string of
125 .I dc
126 commands.
127 .TP
128 .B X
129 Replace the number on the top of the stack with its scale factor.
130 .TP
131 .B "[ ... ]"
132 Put the bracketed
133 text
134 string on the top of the stack.
135 .TP
136 .PD 0
137 .BI < x
138 .TP
139 .BI > x
140 .TP
141 .BI = x
142 .PD
143 Pop and compare the
144 top two elements of the stack.
145 Register
146 .I x
147 is executed if they obey the stated
148 relation.
149 .TP
150 .B v
151 Replace the top element on the stack by its square root.
152 Any existing fractional part of the argument is taken
153 into account, but otherwise the scale factor is ignored.
154 .TP
155 .B !
156 Interpret the rest of the line as a shell command.
157 .TP
158 .B c
159 Clear the stack.
160 .TP
161 .B i
162 The top value on the stack is popped and used as the
163 number base for further input.
164 .TP
165 .B I
166 Push the input base on the top of the stack.
167 .TP
168 .B o
169 The top value on the stack is popped and used as the
170 number base for further output.
171 In bases larger than 10, each `digit' prints as a group of decimal digits.
172 .TP
173 .B O
174 Push the output base on the top of the stack.
175 .TP
176 .B k
177 Pop the top of the stack, and use that value as
178 a non-negative scale factor:
179 the appropriate number of places
180 are printed on output,
181 and maintained during multiplication, division, and exponentiation.
182 The interaction of scale factor,
183 input base, and output base will be reasonable if all are changed
184 together.
185 .TP
186 .B z
187 Push the stack level onto the stack.
188 .TP
189 .B Z
190 Replace the number on the top of the stack with its length.
191 .TP
192 .B ?
193 A line of input is taken from the input source (usually the terminal)
194 and executed.
195 .TP
196 .B "; :"
197 Used by
198 .I bc
199 for array operations.
200 .PP
201 The scale factor set by
202 .B k
203 determines how many digits are kept to the right of
204 the decimal point.
205 If
206 .I s
207 is the current scale factor,
208 .I sa
209 is the scale of the first operand,
210 .I sb
211 is the scale of the second,
212 and
213 .I b
214 is the (integer) second operand,
215 results are truncated to the following scales.
216 .IP
217 .nf
218 \fL+\fR,\fL-\fR max(\fIsa,sb\fR)
219 \fL*\fR min(\fIsa\fR+\fIsb \fR, max\fR(\fIs,sa,sb\fR))
220 \fL/\fI s
221 \fL%\fR so that dividend = divisor*quotient + remainder; remainder has sign of dividend
222 \fL^\fR min(\fIsa\fR\(mu|\fIb\fR|, max(\fIs,sa\fR))
223 \fLv\fR max(\fIs,sa\fR)
224 .fi
225 .SH EXAMPLES
226 .LP
227 Print the first ten values of
228 .IR n !
229 .IP
230 .EX
231 [la1+dsa*pla10>y]sy
232 0sa1
233 lyx
234 .EE
235 .SH SOURCE
236 .B \*9/src/cmd/dc.c
237 .SH "SEE ALSO"
238 .IR bc (1),
239 .IR hoc (1)
240 .SH DIAGNOSTICS
241 .I x
242 .LR "is unimplemented" ,
243 where
244 .I x
245 is an octal number: an internal error.
246 .br
247 `Out of headers'
248 for too many numbers being kept around.
249 .br
250 `Nesting depth'
251 for too many levels of nested execution.
252 .SH BUGS
253 When the input base exceeds 16,
254 there is no notation for digits greater than
255 .BR F .
256 .PP
257 Past its time.