0 and 2p1 are the same point on the unit circle. This is related to Nyquist sampling frequency if my memory still serves me.
Птн, 15 Июл 2011, mijj писал(а): > in the original: > NB. We'll sample a sine wave at 194.18 Hz over 1 second. > NB. Or in other words: our x axis covers 194.18 radians, > NB. and we'll choose our 8000 sample points from that range: > > that's 8000 sample *points* > > 8000 sample points means 7999 sample *intervals* > > ie. the range of (194.18 * 2p1 ) has > 7999 sample intervals and 8000 sample points > > so, in terms of proportion of a segment: > 7999 intervals and 8000 points: > (i. % <:) 8000 NB. ranges from 0 .. 1 > > so ... > > SamplePoints =. 1 o. (194.18 * 2p1 ) * (i. % <:) 8000 > > > > On 2011-07-15 03:09, [email protected] wrote: > > mijj> yeh .. i always confuse samples with sample intervals too .. > > mijj> should be ... > > mijj> x =. 1 o. (194.18 * 2p1 ) * (i. %<:) 8000 > > > > Should be not. So, once more: > > > > The sample interval here is 1r8000 sec (=8kHz > > sampling). For Ian, the one-second signal is "194.14 sine waves", > > and for direct treatment of "sin(x)" function with 1&o., the "x" > > values ("points where the samples are taken") for the periods have > > to be measured in the radians: > > > > x =. (194.18 * 2p1 ) * (i. %<:) 8000 > > > > At every sample point, the sample value ("sample") will be the > > sine value or some scaling thereof: > > > > samples =. ... 1 o. x > > > > Less confused now? > > > > Martin Neitzel > > > > (Before submitting my code last night, I checked a 440 Hz version > > against my tuning fork. You might get one before posting, too.) > > ---------------------------------------------------------------------- > > For information about J forums see http://www.jsoftware.com/forums.htm > > > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm -- regards, ==================================================== GPG key 1024D/4434BAB3 2008-08-24 gpg --keyserver subkeys.pgp.net --recv-keys 4434BAB3 ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
