Hi Doug, 

Thank you for the quick response. I tried the new file, and it fixes the problem with the tnullmax. However, I'm still having trouble computing the right number of tp. If I want a null after every event, that's 96 nulls. If I set the tnullmax/min range at 4-10s, then nulls will have an average duration of 7s, so 96 * 7/2 = 336 tp, plus 96 tp for the stimuli, = 432 tp. But with 432 tp I get a "could not enforce tnullmax" error. Oddly, with a lower ntp (384), I don't get an error, but get extra time at the end (so one null at the end of 70s). Evidently I'm not computing the ntp correctly. Alternatively, could I just cut the final null even down to the right length?   

Thanks again,

Hanah

Hi Hanah, I just found and fixed the bug. It was making the effective 
tNullMax = tNullMin + your specified tNullMax. I've put a new (linux) 
version here:
ftp://surfer.nmr.mgh.harvard.edu/transfer/outgoing/flat/greve/optseq2.linux
doug


On 05/09/2012 06:09 PM, Chapman, Hanah wrote:
> Dear list,
>
> I have an optseq2 question, and would very much appreciate your time.
>
> I'm having difficulty calculating the required number of timepoints. 
> I'd like to use --tnullmin and --tnullmax so as to have a null event 
> in between each trial, with a duration of 4-8 sec. I have 16 
> conditions, 6 repeats/run, 2s trials, 2s TR. I computed that a run 
> would need 16*6 = 96 timepoints for the trials. Then there would be 96 
> null events (to have one between each trial), so with an average 6s 
> duration for nulls, a run needs 96*6/2 = 288 timepoints for the nulls, 
> so 96+288 = 384 tp total. However, when I run optseq2 with these 
> parameters, I still get nulls that are longer than 8s, and there is 
> evidently extra time left over, since the last null event is 70 sec 
> long. I'm using the following code:
>
> --ntp 384  --tr 2 --psdwin 0 20 --tnullmin 4 --tnullmax 8 --nkeep 6 
> --o outfile --nsearch 1000 \
> --ev DD 2 6 \
> --ev DF 2 6 \
> --ev DP 2 6 \
> --ev DN 2 6 \
> --ev FF 2 6 \
> --ev FD 2 6 \
> --ev FN 2 6 \
> --ev FP 2 6 \
> --ev PP 2 6 \
> --ev PD 2 6 \
> --ev PN 2 6 \
> --ev PF 2 6 \
> --ev NN 2 6 \
> --ev ND 2 6 \
> --ev NF 2 6 \
> --ev NP 2 6
>
> I understand that the 4-8s range may be too tight, and relaxing it is 
> not a big deal. However, I tried 4-10s, and still has the problems 
> with nulls > 10s and extra time at the end.
>
> Thank you for your time,
>
> Hanah Chapman
> Postdoctoral Fellow
> The Ohio State University
>
>
>
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