15 lines
396 B
Plaintext
15 lines
396 B
Plaintext
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#!/bin/sh
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# science speak from wikipedia
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! eq $# 2 && printf "Usage: $0 [minuend] [subtrahend]\n" >/dev/stderr && exit 1
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! stris int "$1" && printf "$0: $1: Not an integer\n" >/dev/stderr && exit 1
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! stris int "$2" && printf "$0: $2: Not an integer\n" >/dev/stderr && exit 1
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minuend=$1
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subtrahend=$2
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# (- a b) == (+ a (* b -1))
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printf "%b\n" $(add $minuend $(multiply $subtrahend -1))
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exit 0
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