IRIX Base Documentation 1998 November/IRIX 6.5.2 Base Documentation November 1998.img/usr/share/catman/u_man/cat1/dc.z/dc

Text File | 1998-10-20 | 12KB | 331 lines

DDDDCCCC((((1111))))                                                                    DDDDCCCC((((1111))))



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     _dddd_cccc - an arbitrary precision calculator

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     _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.



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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.







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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.







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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.




















































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