Divide hz into fractions of seconds

hello
I have a pulse (hz) and a envelope generator (sec) and I want the duration of the envelope to be half of the Hz but as simple as that might sound I am getting nowhere.looking for a calculation to get this relationship when I tap my tempo:hz sec0.5 11 0.52 0.254 0.125thanks! 
The period of a wave (seconds) = 1.0 divided by the frequency (Hz)In other words,
s = 1.0 / fwhere s is expressed in seconds, and f is expressed in Hz.For example, 1.0 / 0.5 Hz = 2 secondsThen just divide the seconds by 2.0\. You'll need to multiply the result by 1000 for the Envelope Generator, because the underlying representation is milliseconds.Best Wishes,Mark 
finally got it...
thanks!fubbi