#!/bin/bash

cache_vals(){
    echo "$1" > "$3"
    echo -n "$2" >> "$3"
}

cached_eval(){
    local dir
    local a0
    local t0
    local a1
    local t1
    dir="/tmp/$1"
    a1="$2"
    t1="$3"
    if [ -f "$dir" ]; then
        a0="$(head -n1 "$dir")"
        t0="$(tail -n+2 "$dir")"
        cache_vals "$a1" "$t1" "$dir"
        awk -v a1="$a1" \
            -v t1="$t1" \
            -v a0="$a0" \
            -v t0="$t0" \
            'BEGIN {print (a1-a0)/(t1-t0)}'
    else
        cache_vals "$a1" "$t1" "$dir"
        echo -n 0
    fi
}

fmt_percent(){
    awk "$(printf '%s' \
                   '{x=$1*100} END { '\
                   'if (x>=100) printf("%d%% ", x); '\
                   'else if (x>=10) printf("%.1f%%", x); '\
                   'else printf("%.2f%%", x)'\
                   '}')"
}