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DDDDCCCC((((1111)))) DDDDCCCC((((1111)))) NNNNAAAAMMMMEEEE _dddd_cccc - an arbitrary precision calculator SSSSYYYYNNNNOOOOPPPPSSSSIIIISSSS _dddd_cccc DDDDEEEESSSSCCCCRRRRIIIIPPPPTTTTIIIIOOOONNNN _D_c is a reverse-polish desk calculator which supports unlimited precision arithmetic. It also allows you to define and call macros. Normally _d_c reads from the standard input; if any command arguments are given to it, they are filenames, and _d_c reads and executes the contents of the files before reading from standard input. All normal output is to standard output; all error output is to standard error. A reverse-polish calculator stores numbers on a stack. Entering a number pushes it on the stack. Arithmetic operations pop arguments off the stack and push the results. To enter a number in _d_c, type the digits with an optional decimal point. Exponential notation is not supported. To enter a negative number, begin the number with ``_''. ``-'' cannot be used for this, as it is a binary operator for subtraction instead. To enter two numbers in succession, separate them with spaces or newlines. These have no meaning as commands. PPPPrrrriiiinnnnttttiiiinnnngggg CCCCoooommmmmmmmaaaannnnddddssss pppp Prints the value on the top of the stack, without altering the stack. A newline is printed after the value. PPPP Prints the value on the top of the stack, popping it off, and does not print a newline after. ffff Prints the entire contents of the stack without altering anything. This is a good command to use if you are lost or want to figure out what the effect of some command has been. AAAArrrriiiitttthhhhmmmmeeeettttiiiicccc ++++ Pops two values off the stack, adds them, and pushes the result. The precision of the result is determined only by the values of the arguments, and is enough to be exact. ---- Pops two values, subtracts the first one popped from the second one popped, and pushes the result. **** Pops two values, multiplies them, and pushes the result. The number of fraction digits in the result is controlled by the current precision value (see below) and does not depend on the values being multiplied. //// Pops two values, divides the second one popped from the first one popped, and pushes the result. The number of fraction digits is specified by the precision value. PPPPaaaaggggeeee 1111 DDDDCCCC((((1111)))) DDDDCCCC((((1111)))) %%%% Pops two values, computes the remainder of the division that the //// command would do, and pushes that. The division is done with as many fraction digits as the precision value specifies, and the remainder is also computed with that many fraction digits. ^^^^ Pops two values and exponentiates, using the first value popped as the exponent and the second popped as the base. The fraction part of the exponent is ignored. The precision value specifies the number of fraction digits in the result. vvvv Pops one value, computes its square root, and pushes that. The precision value specifies the number of fraction digits in the result. Most arithmetic operations are affected by the ``precision value'', which you can set with the kkkk command. The default precision value is zero, which means that all arithmetic except for addition and subtraction produces integer results. The remainder operation %%%% requires some explanation: applied to arguments ``a'' and ``b'' it produces ``a - (b * (a / b))'', where ``a / b'' is computed in the current precision. SSSSttttaaaacccckkkk CCCCoooonnnnttttrrrroooollll cccc Clears the stack, rendering it empty. dddd Duplicates the value on the top of the stack, pushing another copy of it. Thus, ``4d*p'' computes 4 squared and prints it. RRRReeeeggggiiiisssstttteeeerrrrssss _D_c provides 256 memory registers, each named by a single character. You can store a number or a string in a register and retrieve it later. ssss_r Pop the value off the top of the stack and store it into register _r. llll_r Copy the value in register _r and push it onto the stack. This does not alter the contents of _r. Each register also contains its own stack. The current register value is the top of the register's stack. SSSS_r Pop the value off the top of the (main) stack and push it onto the stack of register _r. The previous value of the register becomes inaccessible. LLLL_r Pop the value off the top of register _r's stack and push it onto the main stack. The previous value in register _r's stack, if any, is now accessible via the llll_r command. PPPPaaaaggggeeee 2222 DDDDCCCC((((1111)))) DDDDCCCC((((1111)))) Parameters _D_c has three parameters that control its operation: the precision, the input radix, and the output radix. The precision specifies the number of fraction digits to keep in the result of most arithmetic operations. The input radix controls the interpretation of numbers typed in; all numbers typed in use this radix. The output radix is used for printing numbers. The input and output radices are separate parameters; you can make them unequal, which can be useful or confusing. The input radix must be between 2 and 36 inclusive. The output radix must be at least 2. The precision must be zero or greater. The precision is always measured in decimal digits, regardless of the current input or output radix. iiii Pops the value off the top of the stack and uses it to set the input radix. oooo Pops the value off the top of the stack and uses it to set the output radix. kkkk Pops the value off the top of the stack and uses it to set the precision. IIII Pushes the current input radix on the stack. OOOO Pushes the current output radix on the stack. KKKK Pushes the current precision on the stack. SSSSttttrrrriiiinnnnggggssss _D_c can operate on strings as well as on numbers. The only things you can do with strings are print them and execute them as macros (which means that the contents of the string are processed as _d_c commands). All registers and the stack can hold strings, and _d_c always knows whether any given object is a string or a number. Some commands such as arithmetic operations demand numbers as arguments and print errors if given strings. Other commands can accept either a number or a string; for example, the pppp command can accept either and prints the object according to its type. [[[[_c_h_a_r_a_c_t_e_r_s]]]] Makes a string containing _c_h_a_r_a_c_t_e_r_s (contained between balanced [[[[ and ]]]] characters), and pushes it on the stack. For example, [[[[ffffoooooooo]]]]PPPP prints the characters ffffoooooooo (with no newline). xxxx Pops a value off the stack and executes it as a macro. Normally it should be a string; if it is a number, it is simply pushed back onto the stack. For example, [[[[1111pppp]]]]xxxx executes the macro 1111pppp which pushes 1111 on the stack and prints 1111 on a separate line. Macros are most often stored in registers; [[[[1111pppp]]]]ssssaaaa stores a macro to print 1111 into register aaaa, and llllaaaaxxxx invokes this macro. PPPPaaaaggggeeee 3333 DDDDCCCC((((1111)))) DDDDCCCC((((1111)))) >>>>_r Pops two values off the stack and compares them assuming they are numbers, executing the contents of register _r as a macro if the original top-of-stack is greater. Thus, 1111 2222>>>>aaaa will invoke register aaaa's contents and 2222 1111>>>>aaaa will not. <<<<_r Similar but invokes the macro if the original top-of-stack is less. ====_r Similar but invokes the macro if the two numbers popped are equal. ???? Reads a line from the terminal and executes it. This command allows a macro to request input from the user. qqqq exits from a macro and also from the macro which invoked it. If called from the top level, or from a macro which was called directly from the top level, the qqqq command will cause _d_c to exit. QQQQ Pops a value off the stack and uses it as a count of levels of macro execution to be exited. Thus, 3333QQQQ exits three levels. The QQQQ command will never cause _d_c to exit. SSSSttttaaaattttuuuussss IIIInnnnqqqquuuuiiiirrrryyyy ZZZZ Pops a value off the stack, calculates the number of digits it has (or number of characters, if it is a string) and pushes that number. XXXX Pops a value off the stack, calculates the number of fraction digits it has, and pushes that number. For a string, the value pushed is 0. zzzz Pushes the current stack depth; the number of objects on the stack before the execution of the zzzz command. MMMMiiiisssscccceeeellllllllaaaannnneeeeoooouuuussss !!!! Will run the rest of the line as a system command. #### Will interpret the rest of the line as a comment. ::::_r Will pop the top two values off of the stack. The old second-to-top value will be stored in the array _r, indexed by the old top-of-stack value. ;;;;_r Pops the top-of-stack and uses it as an index into the array _r. The selected value is then pushed onto the stack. NNNNOOOOTTTTEEEESSSS The array operations :::: and ;;;; are usually only used by traditional implementations of _b_c. (The GNU _b_c is self contained and does not need _d_c to run.) The comment operator #### is a new command not found in traditional implementations of _d_c. PPPPaaaaggggeeee 4444 DDDDCCCC((((1111)))) DDDDCCCC((((1111)))) BUGS Email bug reports to bbbbuuuugggg----ggggnnnnuuuu----uuuuttttiiiillllssss@@@@pppprrrreeeepppp....aaaaiiii....mmmmiiiitttt....eeeedddduuuu. Be sure to include the word ``dc'' somewhere in the ``Subject:'' field. PPPPaaaaggggeeee 5555 
