t0 (a scalar) is used to calculate T
T is used to calculate ty
T is used to calculate s1
y is the time series of one au
f is a set of indexes taken from ty
ty is used as a set of indexes into y
f is used as a set of indexes into s1

t0
    scalar

T
    1x111
    calculated from t0
    used to calculate ty
    used to calculate s1

y
    192x1
    time series of one au
    indexed by ty

f
    1x55
    set of indexes taken from ty
    used as indexes into ty
    used as indexes into s1

ty
    1x55
    calculated from T
    indexed by f
    used as indexes into y