dc.1 (4834B)

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.