| K1: | Least squares () approximation | (20 routines) |
| K2: | Minimax () approximation | (1 routine) |
| K3: | Least absolute value () approximation | (0 routines) |
| K4: | Other analytic approximations (e.g., Taylor polynomial, Padé) | (1 routine) |
| K5: | Smoothing | (1 routine) |
| K6: | Service routines for approximation | (14 routines) |