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This is Info file dc.info, produced by Makeinfo-1.52 from the input
file dc.texinfo.
This file documents DC, an arbitrary precision calculator.
Published by the Free Software Foundation, 675 Massachusetts Avenue,
Cambridge, MA 02139 USA
Copyright (C) 1984 Free Software Foundation, Inc.
Permission is granted to make and distribute verbatim copies of this
manual provided the copyright notice and this permission notice are
preserved on all copies.
Permission is granted to copy and distribute modified versions of
this manual under the conditions for verbatim copying, provided that
the entire resulting derived work is distributed under the terms of a
permission notice identical to this one.
Permission is granted to copy and distribute translations of this
manual into another language, under the above conditions for modified
versions, except that this permission notice may be stated in a
translation approved by the Foundation.
File: dc.info, Node: Top, Next: Introduction, Prev: (dir), Up: (dir)
* Menu:
* Introduction:: Introduction
* Printing Commands:: Printing Commands
* Arithmetic:: Arithmetic
* Stack Control:: Stack Control
* Registers:: Registers
* Parameters:: Parameters
* Strings:: Strings
* Status Inquiry:: Status Inquiry
* Notes:: Notes
File: dc.info, Node: Introduction, Next: Printing Commands, Prev: Top, Up: Top
Introduction
************
DC is a reverse-polish desk calculator which supports unlimited
precision arithmetic. It also allows you to define and call macros.
Normally DC reads from the standard input; if any command arguments are
given to it, they are filenames, and DC reads and executes the contents
of the files before reading from standard input. All output is to
standard output.
To exit, use `q'. `C-c' does not exit; it is used to abort macros
that are looping, etc. (Currently this is not true; `C-c' does exit.)
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 DC, 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.
File: dc.info, Node: Printing Commands, Next: Arithmetic, Prev: Introduction, Up: Top
Printing Commands
*****************
`p'
Prints the value on the top of the stack, without altering the
stack. A newline is printed after the value.
`P'
Prints the value on the top of the stack, popping it off, and does
not print a newline after.
`f'
Prints the entire contents of the stack and the contents of all of
the registers, 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.
File: dc.info, Node: Arithmetic, Next: Stack Control, Prev: Printing Commands, Up: Top
Arithmetic
**********
`+'
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 flag (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 flag.
`%'
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 flag 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 flag specifies the
number of fraction digits in the result.
`v'
Pops one value, computes its square root, and pushes that. The
precision flag specifies the number of fraction digits in the
result.
Most arithmetic operations are affected by the "precision flag",
which you can set with the `k' 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.
File: dc.info, Node: Stack Control, Next: Registers, Prev: Arithmetic, Up: Top
Stack Control
*************
`c'
Clears the stack, rendering it empty.
`d'
Duplicates the value on the top of the stack, pushing another copy
of it. Thus, `4d*p' computes 4 squared and prints it.
File: dc.info, Node: Registers, Next: Parameters, Prev: Stack Control, Up: Top
Registers
*********
DC provides 128 memory registers, each named by a single ASCII
character. You can store a number in a register and retrieve it later.
`sR'
Pop the value off the top of the stack and store it into register
R.
`lR'
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.
`SR'
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.
`LR'
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 `lR' command.
The `f' command prints a list of all registers that have contents
stored in them, together with their contents. Only the current
contents of each register (the top of its stack) is printed.
File: dc.info, Node: Parameters, Next: Strings, Prev: Registers, Up: Top
Parameters
**********
DC 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. Each radix must be
between 2 and 36 inclusive. The precision must be zero or greater.
The precision is always measured in decimal digits, regardless of the
current input or output radix.
`i'
Pops the value off the top of the stack and uses it to set the
input radix.
`o'
`k'
Similarly set the output radix and the precision.
`I'
Pushes the current input radix on the stack.
`O'
`K'
Similarly push the current output radix and the current precision.
File: dc.info, Node: Strings, Next: Status Inquiry, Prev: Parameters, Up: Top
Strings
*******
DC 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 DC commands).
Both registers and the stack can hold strings, and DC 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 `p' command can accept either and prints the object
according to its type.
`[CHARACTERS]'
Makes a string containing CHARACTERS and pushes it on the stack.
For example, `[foo]P' prints the characters `foo' (with no
newline).
`x'
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, `[1p]x' executes the macro `1p',
which pushes 1 on the stack and prints `1' on a separate line.
Macros are most often stored in registers; `[1p]sa' stores a macro
to print `1' into register `a', and `lax' invokes the macro.
`>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, `1 2>a' will invoke
register `a''s contents and `2 1>a' 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.
This can also be validly used to compare two strings for equality.
`?'
Reads a line from the terminal and executes it. This command
allows a macro to request input from the user.
`q'
During the execution of a macro, this comand does not exit DC.
Instead, it exits from that macro and also from the macro which
invoked it (if any).
`Q'
Pops a value off the stack and uses it as a count of levels of
macro execution to be exited. Thus, `3Q' exits three levels.
File: dc.info, Node: Status Inquiry, Next: Notes, Prev: Strings, Up: Top
Status Inquiry
**************
`Z'
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.
`X'
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 -1.
`z'
Pushes the current stack depth; the number of objects on the stack
before the execution of the `z' command.
`I'
Pushes the current value of the input radix.
`O'
Pushes the current value of the output radix.
`K'
Pushes the current value of the precision.
File: dc.info, Node: Notes, Prev: Status Inquiry, Up: Top
Notes
*****
The `:' and `;' commands of the Unix DC program are not supported,
as the documentation does not say what they do. The `!' command is not
supported, but will be supported as soon as a library for executing a
line as a command exists.
Tag Table:
Node: Top960
Node: Introduction1440
Node: Printing Commands2603
Node: Arithmetic3211
Node: Stack Control5168
Node: Registers5468
Node: Parameters6586
Node: Strings7659
Node: Status Inquiry9857
Node: Notes10571
End Tag Table
|
