The Fractional Part block removes the integer part of a single control input and writes what remains — the signed fraction after the decimal point — to a control output. For example 3.75 gives 0.75 and -1.25 gives -0.25. It is a control-domain math operator with no adjustable parameters.
On every tick it reads the incoming control value and applies the standard-library modf function, which splits the value into its integer and fractional parts; the fractional part is stored on the output control pin. It holds no state and processes one sample-frame per tick, in step with WaveWarp's sample-per-sample engine.