DTWDT Functions

USAGE: err = computeErrorFunction( u1, u0, nSample, lag )

INPUT:

u1 = trace that we want to warp; size = (nsamp,1)

u0 = reference trace to compare with: size = (nsamp,1)

nSample = numer of points to compare in the traces

lag = maximum lag in sample number to search

norm = 'L2' or 'L1' (default is 'L2')

OUTPUT:

err = the 2D error function; size = (nsamp,2*lag+1)

The error function is equation 1 in Hale, 2013.

You could umcomment the L1 norm and comment the L2 norm if you want on Line 29

Original by Di Yang Last modified by Dylan Mikesell (25 Feb. 2015)

USAGE: d = accumulationdiwmod( dir, err, nSample, lag, b )

INPUT:

dir = accumulation direction ( dir > 0 = forward in time, dir <= 0 = backward in time)

err = the 2D error function; size = (nsamp,2*lag+1)

nSample = numer of points to compare in the traces

lag = maximum lag in sample number to search

b = strain limit (integer value >= 1)

OUTPUT:

d = the 2D distance function; size = (nsamp,2*lag+1)

The function is equation 6 in Hale, 2013.

Original by Di Yang Last modified by Dylan Mikesell (25 Feb. 2015)

USAGE: stbar = backtrackDistanceFunction( dir, d, err, lmin, b )

INPUT:

dir = side to start minimization ( dir > 0 = front, dir <= 0 = back)

d = the 2D distance function; size = (nsamp,2*lag+1)

err = the 2D error function; size = (nsamp,2*lag+1)

lmin = minimum lag to search over

b = strain limit (integer value >= 1)

OUTPUT:

stbar = vector of integer shifts subject to |u(i)-u(i-1)| <= 1/b

The function is equation 2 in Hale, 2013.

Original by Di Yang Last modified by Dylan Mikesell (19 Dec. 2014)

Compute the accumulated error along the warping path for Dynamic Time Warping.

USAGE: function error = computeDTWerror( Aerr, u, lag0 )

INPUT:

Aerr = error MATRIX (equation 13 in Hale, 2013)

u = warping function (samples) VECTOR

lag0 = value of maximum lag (samples) SCALAR

Written by Dylan Mikesell Last modified: 25 February 2015