Feature detection:  the math
TP_tmp.emf
This can be rewritten:
TP_tmp.emf
Eigenvalues and eigenvectors of H
•Define shifts with the smallest and largest change (E value)
•x+ = direction of largest increase in E.
•l+ = amount of increase in direction x+
•x- = direction of smallest increase in E.
•l- = amount of increase in direction x+
•
 x-
 x+
TP_tmp.emf TP_tmp.emf