Difference between revisions of "Cross correlation matrix"

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(Created page with "Category:classification Category:PCA The cross correlation matrix (often called ''ccmatrix'' in ''Dynamo'' jargon) of a set of ''N'' particles is an ''N X N'' matrix....")
 
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This similarity of particles ''i'' and ''j''  measured in terms of the normalized cross correlation of the the two aligned particles, filtered to their common fourier components, and  restricted to a region in direct space (indicated by a classification mask). The pseudo code will run as:
 
This similarity of particles ''i'' and ''j''  measured in terms of the normalized cross correlation of the the two aligned particles, filtered to their common fourier components, and  restricted to a region in direct space (indicated by a classification mask). The pseudo code will run as:
 
<code>
 
<code>
% read particle i  -> Pi
+
 
% rotate and shift particles ''i''
+
# read particle i  -> Pi
% create the missing wedge of particle
+
 
% rotate missing wedge of particles ''i'' ''RiWi''  
+
# rotate and shift particles ''i''
% compute Fourier coefficients  common to Cij
+
 
 +
# create the missing wedge of particle
 +
# rotate missing wedge of particles ''i'' ''RiWi''  
 +
# compute Fourier coefficients  common to Cij
 
</code>
 
</code>
  

Revision as of 10:35, 19 April 2016


The cross correlation matrix (often called ccmatrix in Dynamo jargon) of a set of N particles is an N X N matrix. Each entry (i,j) represents the similarity of particles i and j in the data set.

Definition of similarity

This similarity of particles i and j measured in terms of the normalized cross correlation of the the two aligned particles, filtered to their common fourier components, and restricted to a region in direct space (indicated by a classification mask). The pseudo code will run as:

  1. read particle i -> Pi
  1. rotate and shift particles i
  1. create the missing wedge of particle
  2. rotate missing wedge of particles i RiWi
  3. compute Fourier coefficients common to Cij


Input of a ccmatrix

Computation of ccmatrix

Application of a ccmatrix