fretting tolerance calculators

all other things being equal, this is how changes in length affect frequency in cents, i think.
the equation looks like this in javascript: Math.round(1200*Math.log(baseLength/otherLength)/Math.log(2)*centPrec)/centPrec

given two lengths what is the ratio of their frequencies in cents

ideal fretted string length
actual fretted string length
error in cents

a misplaced fret, how much out of tune does it sound?

scale length
ideal fret distance to nut
actual fret distance to nut
error in cents

i can only fret so accurately, how bad will it sound?

scale length
fretting accuracy (+/- unit)
error in cents

i want it to sound this good, how accurately do I have to fret it?

scale length
acceptable error (+/- cents)
required accuracy