反函數

inverse function (math.)

contrary / in reverse / inside out or upside down / to reverse / to return / to oppose / opposite / against / anti- / to rebel / to use analogy / instead / abbr. for 反切[fan3 qie4] phonetic system

envelope / case / letter

variant of 函[han2]

function (math.)

to count / to count as / to regard as / to enumerate (sb's shortcomings)

number / figure / several / CL:個|个[ge4]

frequently / repeatedly