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**NAME**

dc - desk calculator

**SYNOPSIS**

dc[file]

**DESCRIPTION**

Dcis an arbitrary precision desk calculator. 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 ofdcis 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 digits0-9A-For0-9a-f. A hexadecimal number beginning with a lower case letter must be preceded by a zero to distinguish it from the command associated with the letter. It may be preceded by an underscore_to input a negative number. Numbers may contain decimal points. + - / * % ^ Add subtract multiply divide remainder or exponentiate the top two values on the stack. 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.sxSxPop the top of the stack and store into a register namedx, wherexmay be any character. Under operationSregisterxis treated as a stack and the value is pushed on it.lxLxPush the value in registerxonto the stack. The registerxis not altered. All registers start with zero value. Under operationLregisterxis treated as a stack and its top value is popped onto the main stack.dDuplicate the top value on the stack.pPrint the top value on the stack. The top value remains unchanged.Pinterprets the top of the stack as an text string, removes it, and prints it.fPrint the values on the stack.qQExit the program. If executing a string, the recursion level is popped by two. Under operationQthe top value on the stack is popped and the string execution level is popped by that value.xTreat the top element of the stack as a character string and execute it as a string ofdccommands.XReplace the number on the top of the stack with its scale factor.[...]Put the bracketed text string on the top of the stack.<x>x=xPop and compare the top two elements of the stack. Registerxis executed if they obey the stated relation.vReplace 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.!Interpret the rest of the line as a shell command.cClear the stack.iThe top value on the stack is popped and used as the number base for further input.IPush the input base on the top of the stack.oThe top value on the stack is popped and used as the number base for further output. In bases larger than 10, each `digit' prints as a group of decimal digits.OPush the output base on the top of the stack.kPop the top of the stack, and use that value 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.zPush the stack level onto the stack.ZReplace 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 bybcfor array operations. The scale factor set bykdetermines how many digits are kept to the right of the decimal point. Ifsis the current scale factor,sais the scale of the first operand,sbis the scale of the second, andbis the (integer) second operand, results are truncated to the following scales. +,- max(sa,sb) * min(sa+sb, max(s,sa,sb)) /s%so that dividend = divisor*quotient + remainder; remainder has sign of dividend ^ min(sa×|b|, max(s,sa)) v max(s,sa)

**EXAMPLES**

Print the first ten values ofn! [la1+dsa*pla10>y]sy 0sa1 lyx

**SOURCE**

/src/cmd/dc.c

**SEE** **ALSO**

bc(1),hoc(1)

**DIAGNOSTICS**

xwherexis an octal number: an internal error. `Out of headers' for too many numbers being kept around. `Nesting depth' for too many levels of nested execution.

**BUGS**

When the input base exceeds 16, there is no notation for digits greater thanF. Past its time. DC(1plan9)