keyword  type  mini sample  keyword sequence is insignificant 
XVector  vec  XV=year  (required) a vector with N nodes of the independent variable in rising order

YVector  arr  YV=linear  (required)

Init    Init  (required on 1st call to cubic interpolation) to initialize the Akima coefficients 
Xi  num  X=3.1  interpolate at Xi, default is Xi=0 
X2  num  x2=3.9  integrate the interpolated data from Xi to X2 
Find  num  find=y  find x closest to Xi with interpolated value equal to y 
DYdx    dy  1st derivative of interpolated data at Xi 
DYdx  num  dy=yprime  find x closest to Xi with 1st derivative equal to yprime 
D2ydx    d2y  2nd derivative of interpolated data at Xi 
D2ydy  num  d2y=y2prime  find x closest to Xi with 2nd derivative equal to y2prime 
ERror  LBL  ER=99  on error jump to ⇒ label 99 