<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><br><div><div>On Aug 5, 2009, at 9:21 AM, Sacks, Annette E wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0; "><div lang="EN-US" link="blue" vlink="purple"><div class="Section1"><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman'; "><font size="2" face="Courier New"><span style="font-size: 10pt; font-family: 'Courier New'; ">I've been doing a channel cross-coherence analysis in EEGlab v6.01b using newcrossf() with a sampling freq of 250Hz, epoch start/end [-400 1896], and frequency range [0 100], which outputs a 102 x 200 coherence matrix. This is the call I used:<o:p></o:p></span></font></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman'; "><font size="2" face="Courier New"><span style="font-size: 10pt; font-family: 'Courier New'; "><o:p> </o:p></span></font></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman'; "><font size="2" face="Courier New"><span style="font-size: 10pt; font-family: 'Courier New'; ">>> [coh,mcoh,timesout,freqsout,cohboot,cohangles] = pop_newcrossf(EEG, 1, 1, 2, [-400 1896], 0, 'freqs', [0 100], 'alpha', .05);<o:p></o:p></span></font></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman'; "><font size="2" face="Courier New"><span style="font-size: 10pt; font-family: 'Courier New'; "><o:p> </o:p></span></font></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman'; "><font size="2" face="Courier New"><span style="font-size: 10pt; font-family: 'Courier New'; ">Which gives this output:<o:p></o:p></span></font></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman'; "><font size="2" face="Courier New"><span style="font-size: 10pt; font-family: 'Courier New'; "><o:p> </o:p></span></font></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman'; "><font size="2" face="Courier New"><span style="font-size: 10pt; font-family: 'Courier New'; ">Adjust min freq. to 0.98 Hz to match FFT output frequencies Adjust max<o:p></o:p></span></font></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman'; "><font size="2" face="Courier New"><span style="font-size: 10pt; font-family: 'Courier New'; ">freq. to 99.61 Hz to match FFT output frequencies Generating 200 time<o:p></o:p></span></font></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman'; "><font size="2" face="Courier New"><span style="font-size: 10pt; font-family: 'Courier New'; ">points (-143.6 to 1639.6 ms) The window size used is 128 samples (512<o:p></o:p></span></font></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman'; "><font size="2" face="Courier New"><span style="font-size: 10pt; font-family: 'Courier New'; ">ms) wide. Estimating 102 linear-spaced frequencies from 1.0 Hz to 99.6 Hz.<o:p></o:p></span></font></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman'; "><font size="2" face="Courier New"><span style="font-size: 10pt; font-family: 'Courier New'; "><o:p> </o:p></span></font></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman'; "><font size="2" face="Courier New"><span style="font-size: 10pt; font-family: 'Courier New'; ">My question is: how do I calculate exactly how the time and frequency bins are being split up in the 102x200 (freq x time) coh matrix ?<o:p></o:p></span></font></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman'; "><font size="2" face="Courier New"><span style="font-size: 10pt; font-family: 'Courier New'; ">ie, we don't know the exact beginning and ending time/frequency that is being collected in each entry of the coh matrix.</span></font></div></div></div></span></blockquote><div><br></div><div><br></div><div>The <i>freqsout</i> and <i>timesout</i> matrices contain the actual time latencies and frequencies. When you use FFT, even if you specify actual frequencies 'freqs', [1 2 3 4 5 6 7.... ] (which is possible), the FFT decomposition is run based on your window size and the function then searches for frequencies closest to the one you have asked for. When you use wavelets, you get the decomposition at the frequency you have actually asked for. </div><div><br></div><div>To obtain round frequencies for FFT, just choose a window size multiple of the sampling rate. For instance 250, 125, etc...</div><div><br></div><div>Hope this helps,</div><div><br></div><div>Arno </div><div><br></div><br><blockquote type="cite"><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0; "><div lang="EN-US" link="blue" vlink="purple"><div class="Section1"><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman'; "><font size="2" face="Courier New"><span style="font-size: 10pt; font-family: 'Courier New'; "><o:p></o:p></span></font></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman'; "><font size="2" face="Courier New"><span style="font-size: 10pt; font-family: 'Courier New'; "><o:p> </o:p></span></font></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman'; "><font size="2" face="Courier New"><span style="font-size: 10pt; font-family: 'Courier New'; ">Thanks,<o:p></o:p></span></font></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman'; "><font size="2" face="Courier New"><span style="font-size: 10pt; font-family: 'Courier New'; ">Annette Sacks</span></font><font size="2" face="Arial"><span style="font-size: 10pt; font-family: Arial; "><o:p></o:p></span></font></div><span><ATT00001.txt></span></div></div></span></blockquote></div><br></body></html>