| K1: | Least squares (L2) approximation | (12 routines) |
| K2: | Minimax (L∞) approximation | (0 routines) |
| K3: | Least absolute value (L1) approximation | (0 routines) |
| K4: | Other analytic approximations (e.g., Taylor polynomial, Padé) | (1 routine) |
| K5: | Smoothing | (1 routine) |
| K6: | Service routines for approximation | (10 routines) |