the method constructs an object from a function a timerange where it is valid and a format
Arguments
map
a function of one argument (time)
starttime
the point in time from which map is a valid representation
endtime
the point in time until which map is a valid representation
lag
a scalar describing the time lag. Positive Values shift the argument of the interpolation function forward in time. (retard its effect)
format
a string that specifies the format used to represent the atmospheric fraction. Possible values are "Delta14C" which is the default or "afn" the Absolute Fraction Normal representation