# Hncoca.m

Magnitude-mode HNCOCA pulse sequence from

               http://dx.doi.org/10.1007/BF01874573


using the bidirectional propagation method described in

            http://dx.doi.org/10.1016/j.jmr.2014.04.002


The sequence is hard-wired to work on 1H,13C,15N proteins. Syntax:

            fid=hncoca(spin_system,parameters,H,R,K)


where H is the hamiltonian commutation superoperator, R is the re- relaxation superoperator and K is the chemical kinetics superope- rator. The following parameters are required:

     parameters.npoints   - a vector of three integers giving the
number of points in the three temporal
dimensions, ordered as [t1 t2 t3].

     parameters.sweep     - a vector of three real numbers giving
the sweep widths in the three frequen-
cy dimensions, ordered as [f1 f2 f3].

     parameters.tau       - the four delays required for the ope-
ration of the sequence (see the paper)
in seconds. Reasonable values are
[2.25e-3, 2.75e-3, 8.00e-3, 7.00e-3]


Frequency dimensions: F1 is N, F2 is CA, F3 is H.

Note: spin labels must be set to PDB atom IDs ('CA', 'HA', etc.) in sys.labels for this sequence to work properly.