A numerical atlas database of harmonic characteristic parameters comprising 41601 basic dimensional types has been set up. An approach employed to synthesize approximate double straight-line path with prescribed timing is realized using numerical atlas method. Errors between the given path and the actual path have been classified and defined as point-to-point error and normal error. Errors of each mechanism synthesized have been obtained including mean point-to-point error

maximal point-to-point error

mean normal error and maximal normal error. The results provide reliable reference data for the designer. It is proved that the method is available by an example.