64 lines
1.7 KiB
Groff
64 lines
1.7 KiB
Groff
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.\" Copyright (c) 2024 Emma Tebibyte <emma@tebibyte.media>
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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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.TH rpn 1
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.SH NAME
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npc \(en reverse polish notation evaluation
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.SH SYNOPSIS
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rpn [integers...] [operations...]
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.SH DESCRIPTION
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Rpn parses reverse polish notation and adds characters to the stack until there
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is an operation. See rpn(7) for more details on the syntax of reverse polish
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notation.
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.SH STANDARD INPUT
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If rpn is passed arguments, it interprets those arguments as an expression to
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be evaluated. Otherwise, it reads characters from standard input to add to the
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stack.
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.SH DIAGNOSTICS
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If encountering a syntax error, rpn will exit with the appropriate error code
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as defined by sysexits.h(3) and print an error message.
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.SH CAVEATS
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Due to the complexity of integer storage in memory, rpn is only capable of
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parsing decimal integers.
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Additionally, due to the laws of physics, floating-point math can only be as
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precise as slightly less than the machine epsilon of the hardware on which rpn
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is running.
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.SH RATIONALE
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POSIX has its own calculator in the form of bc(1p), which uses standard input
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for its calculations. Pair the clunkiness of piping expressions into it and its
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use of standard notation, it was clear what rpn should be.
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There are no mathematics in the qi(1) shell because it was decided early on that
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math was the job of a specific tool and not the shell itself. Thus, rpn was
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born.
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.SH AUTHOR
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Written by Emma Tebibyte <emma@tebibyte.media>.
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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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.SH SEE ALSO
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bc(1p), dc(1)
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