Hi,all:
When calculating the first eigenvector, I found a problem. I used two
different ptraj.in files and got an opposite result of eigenvector.
first ptraj1.in (I just calculated the first eigenvector):
rms first .CA
matrix covar name cvmat .CA out cvmat.dat
analyze matrix cvmat out eigen_covar.dat vecs 1
first result:
 1  6682.90154
-0.02344    0.00701    0.00270   -0.00799    0.00716    0.00631
0.00676
 0.01184    0.01257    0.00844    0.01400    0.01116    0.00726
0.01468
 ... ...
second ptraj2.in (the difference is that I calculate the first two
eigenvectors, but the very first eigenvector is what I want):
rms first .CA
matrix covar name cvmat .CA out cvmat.dat
analyze matrix cvmat out eigen_covar.dat vecs 2
second result:
 1  6682.90154
 0.02344   -0.00701   -0.00270    0.00799   -0.00716   -0.00631
-0.00676
-0.01184   -0.01257   -0.00844   -0.01400   -0.01116   -0.00726
-0.01468
 ... ...
We can see the sign of values is opposite. I have no idea why this
happened? Does anybody point me out?
Thanks in advance,
Qi
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Received on Sun Jun 08 2008 - 06:08:21 PDT