How can I perform 'Hierarchical Clustering' by Absolute value of correlation?

>> x
x =
     1     2     3     4
     2     3     2     3
     1     2     3     4
     4     3     2     1

>> pdist(x,'cor')
ans =
    0.5528         0    2.0000    0.5528    1.4472    2.0000

>> 1-corr(x')
ans =
         0    0.5528         0    2.0000
    0.5528         0    0.5528    1.4472
         0    0.5528         0    2.0000
    2.0000    1.4472    2.0000         0

1) The first way is to compute the distance as one minus the absolute correlation, and compute linkage based on that.

>> D = pdist(x,'cor');

>> linkage(D,'single')
ans =
    1.0000    3.0000         0
    2.0000    5.0000    0.5528
    4.0000    6.0000    1.4472

>> C = 1-D % get correlation
C =
    0.4472    1.0000   -1.0000    0.4472   -0.4472   -1.0000

>> D = 1-abs(C) % get 1-abs(correlation)
D =
    0.5528         0         0    0.5528    0.5528         0

>> linkage(D,'single') % cluster using that
ans =
    3.0000    4.0000         0
    1.0000    5.0000         0
    2.0000    6.0000    0.5528

Notice that points 1,3,4 are clustered with zero distance, even though the correlation with the point 4 is '-1'.

2) The second way is to write the distance into the 'linkage' command:

>> linkage(x,'single',@(xrow,ymat) 1-abs(corr(xrow',ymat')))
ans =
    3.0000    4.0000         0
    1.0000    5.0000         0
    2.0000    6.0000    0.5528