[Eeglablist] about the pop_runica rank problem

[Arnaud Delorme]

Dear Josh,

yes, if you are decreasing the rank yourself, the rank computation issue (which should not be an issue any more) does not apply to you.
yes also for double precision. The precision is changed automatically. Note that the matrix rank is also computed using double precision.

Best,

Arno

On Aug 23, 2012, at 9:15 AM, Joshua Hartshorne wrote:

> I am using PCA to identify and remove artifact (mostly blinks) from the channel data. I use EGI, so my data is automatically average-referenced, and I haven't seen any reason to change the reference to something else. Probably for this reason, I get the rank warning from pop_runica that has been discussed in this forum.
> 
> As I said, I'm using PCA ("jader" with 24 components, down from 128 channels). My understanding from previous posts to this listserv is that since I'm decreasing rank anyway, the rank computation issue doesn't really affect me. Is that correct? My blink components generally look pretty good, and removing them from the channel data results in what appears to be blink-free data, so that increases my confidence that everything is working correctly. But I'd like to confirm this.
> 
> I also had a question about double-precision. Based on the output I get from pop_runica, it seems that the actual computations (though maybe not the rank calculation) is done using double-precision, and that I don't need to manually change my data to double-precision? In any case, I haven't been able to figure out how to do that manual conversion, so I'd appreciate directions on that if necessary. I use the most recent update of v10. I know the latest update of v11 now does the rank calculation with double-precision, but that seems unnecessary for my purposes, if what I wrote in the last paragraph is right.
> 
> Many thanks for your help.
> Josh Hartshorne
> 
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