85 lines
2.5 KiB
Groff
85 lines
2.5 KiB
Groff
.\" Copyright (c) 2024 Emma Tebibyte <emma@tebibyte.media>
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.\" Copyright (c) 2024 DTB <trinity@trinity.moe>
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.\"
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.\" This work is licensed under CC BY-SA 4.0. To see a copy of this license,
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.\" visit <http://creativecommons.org/licenses/by-sa/4.0/>.
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.\"
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.TH RPN 1 2024-06-06 "Bonsai Core Utilites 0.13.8"
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.SH NAME
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rpn \(en reverse polish notation evaluation
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.\"
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.SH SYNOPSIS
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rpn
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.RB [ numbers... ]
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.RB [ operators... ]
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.\"
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.SH DESCRIPTION
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Evaluate reverse polish notation.
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The program evaluates reverse polish notation expressions either read from the
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standard input or parsed from provided arguments. See the STANDARD INPUT
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section.
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Upon evaluation, the program will print the resulting number on the stack to the
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standard output. Any further specified numbers will be placed at the end of the
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stack.
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For information on for reverse polish notation syntax, see
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.BR rpn (7).
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.\"
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.SH STANDARD INPUT
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If arguments are passed, they are interpreted as an expression to be
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evaluated. Otherwise, it reads whitespace-delimited numbers and operations from
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the standard input.
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.\"
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.SH DIAGNOSTICS
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In the event of an error, a debug message will be printed and the program will
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exit with the appropriate
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.BR sysexits.h (3)
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error code; however, in the event of a syntax error, the program will print an
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error message and continue accepting input.
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.\"
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.SH CAVEATS
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Due to precision constraints and the way floats are represented in accordance
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with the IEEE Standard for Floating Point Arithmetic (\fIIEEE 754\fP),
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floating-point arithmetic has rounding errors. This is somewhat curbed by using
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the machine epsilon as provided by the Rust standard library to which to round
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numbers. Because of this, variation is expected in the number of decimal places
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the program can handle based on the platform and hardware of any given machine.
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.\"
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.SH RATIONALE
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An infix notation calculation utility,
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.BR bc (1p),
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is included in the POSIX standard, but does not accept expressions as arguments;
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in scripts, any predefined, non-interactive input must be piped into the
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program. A
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.BR dc (1)
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pre-dates the standardized
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.BR bc (1p),
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the latter originally being a preprocessor for the former, and was included in
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UNIX v2 onward. While it implements reverse polish notation, it still suffers
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from being unable to accept an expression as an argument.
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.\"
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.SH AUTHOR
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Written by Emma Tebibyte
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.MT emma@tebibyte.media
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.ME .
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.\"
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.SH COPYRIGHT
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Copyright (c) 2024 Emma Tebibyte. License AGPLv3+: GNU AGPL version 3 or later
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<https://gnu.org/licenses/agpl.html>.
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.\"
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.SH SEE ALSO
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.BR bc (1p),
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.BR dc (1),
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.BR rpn (7),
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.I IEEE 754
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