Date of this Version
A complete table of extension factors for all lengths of part records can be approximated closely from a much smaller table of reciprocals of the factors. The procedure is to use linear interpolation on the reciprocals from the small table. The required extension factor is the reciprocal of the result of interpolation. This procedure is more accurate than interpolation on the factors themselves since the reciprocals are more nearly linearly related to length of part record than are the extension factors themselves.