Split a vector where NaN appears

I have many m*3 vectors, and for some of them, they are say, between rows p and q, (which are different for each vector) a number of NaN values in the first column. In these instances, I wish to split them into two vectors, one which contains all rows up to p, and one which contains all rows after q.

To clarify, all the NaN values appear between rows p and q, and there are no values which I wish to keep within these rows.

Answer 1

[dpb]

>> x=randn(10,1);x([4 7])=nan
x =
    0.5080
    0.2820
    0.0335
       NaN
    1.1275
    0.3502
       NaN
    0.0229
   -0.2620
   -1.7502
>> [pq]=[find(isnan(x),1)-1 find(isnan(x),1,'last')+1]
pq =
     3     8
>>