psh-fractional/division/div
2022-01-24 14:58:36 -05:00

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#!/bin/sh
s() {
n=$1; i=1; while [ "$n" -le $2 ]; do
echo "$n"; : $((n+=i))
done
} # seq
fd() { # return first digit of $1
x="$1"; until [ "${#x}" -eq 1 ]; do
x="${x%?}"
done
echo "$x"
}
ld() { # $1/$2
di="$1"; div="$2"; count="$3"; : $((count-=1))
case "$div" in
*'.'*)
sp=0; sdiv="${div%%.*}"; IFS="."; set -- ${div}; div="${1}${2}"; unset IFS
sp="$((${#div}-${#sdiv}))"
esac
# determine where the decimal point is -- if present
case "$di" in
*'.'*)
dp=0; t="$di"; while :; do # use while true + case/break
t="${t#?}"; : $((dp+=1))
case "$t" in
'.'*) break
esac
done
;;
*) dp=0
esac
[ "$dp" -gt 0 ] && {
IFS="."; set -- ${di}; di="${1}${2}"; unset IFS
}
[ "$sp" ] && {
ss="${#di}"; : $((ss-=dp)); : $((ss+=sp)); : $((ss+=1))
until [ "${#di}" -eq "$ss" ]; do
di="${di}0"
done
}
o="$((di/div))"; dp="${#o}"; [ "${#o}" -eq 0 ] && : $((count+=2))
: $((count+=${#o})); until [ "${#di}" -eq "$count" ]; do
di="${di}0"
done
unset IFS o; for i in $(s 1 $count); do
fd="$(fd $di)" # fd is needed later
#echo "$fd"
[ "$i" -gt 1 ] && {
fd="${sd}${fd}"
#echo "$fd"
}
sd="$((fd/div))"; o="${o}${sd}"; sd="$((sd*div))"; sd="$((fd-sd))"
[ "$sd" -eq 0 ] && break
# now pull down # redefine $di
di="${di#?}" # $fd$sd
done
until [ "${o#0}" = "$o" ]; do
o="${o#0}"
done
[ "$dp" -gt 0 ] && {
[ "$t" ] || : $((dp+=1))
[ "$sp" -o "$t" ] && : $((dp-=1))
[ "$((di/div))" -eq 0 ] && o="0$o"
do="$o"; until [ "${#do}" -eq "$dp" ]; do
do="${do%?}"
done
o="$do.${o#$do}"
}
until [ "${o#0}" = "$o" ]; do
o="${o#0}"
done
echo "$o"
}
# 9 decimal points unless $3 is passed
[ "$1" -a "$2" ] && ld "$1" "$2" "${3:-9}"