Bandwidth Restriction

Because the areal segments generated from the angle and distance classes increase in area as the lag distance increases, it is sometimes desirable to restrict this area (Deutsch and Journel; 1992, p. 45). If you specify the BANDW= option in the COMPUTE statement, the lateral, or perpendicular, distance from the axis defining the angle classes is fixed.

For example, suppose two points , are picked from the domain in Figure 95.11 and are superimposed on the grid defining distance and angle classes, as shown in Figure 95.15.

The endpoint of vector falls within the angle class around and the th lag class; however, it falls outside the restricted area defined by the bandwidth. Hence, it is excluded from the semivariance calculation.

Figure 95.15 Selected Pair Falls Outside Bandwidth Limit

Finally, a pair that falls in a lag class larger than the value of the MAXLAGS= option is excluded from the semivariance calculation.

The BANDW= option complements the angle and lag tolerances in determining how point pairs are included in distance classes. Clearly, the number of pairs within each angle/distance class is strongly affected by the angle and lag tolerances and whether BANDW= has been specified. See also the section Angle Classification for more details about the effects these rules can have, since BANDW= operates in a manner similar to the ATOL= option.