floating point index - interpolates data in case of non-integer indices

Y=flix(D,x)
FLIX returns Y=D(x) if x is an integer
otherwise D(x) is interpolated from the neighbors D(ceil(x)) and D(floor(x))

Applications:
(1)  discrete Dataseries can be upsampled to higher sampling rate
(2)  transformation of non-equidistant samples to equidistant samples
(3)  [Q]=flix(sort(D),q*(length(D)+1)) calculates the q-quantile of data series D

FLIX(D,x) is the same as INTERP1(D,X,'linear'); Therefore, FLIX might
become obsolete in future.

see also: HIST2RES, Y2RES, PLOTCDF, INTERP1