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Figure D-13. Saving or running a batch job through the Interpolate 
screen. "Save to Batch Job" saves the values that have been entered in 
the fields on this screen into the "Batch File ('filename'.job)". If the 'file- 
name'.job file already exists, the new entry is appended to the existing 
file. If it does not exist, a new file is created. The "Output File" file name 
entry is also written to a file ('filename'.fls) for use in creating volume 
and mass estimates by running batch jobs. The .fls file is simply a list of 
interpolated (.est) file names that can be processed sequentially. The 
"Test Batch Job" button executes a batch job but does not run the inter¬ 
polator. This button can be used to test whether the needed files exist 
and the batch job is sound prior to execution of the interpolator. 
MATH BUTTON 
Click the Math Button if you need to conduct special operations on one or more 
files. Four functions are provided: 1) Math operations which include adding, 
subtracting, multiplying, or dividing one interpolated file by another, or by a 
constant; 2) Recoding values to new values; 3) Conducting a change analysis over 
time; and, 4) Calculating the minimum or maximum values from a set of files. 
Math functionality is provided so that special parameters can be calculated. Math is 
conducted on a cell by cell basis. For instance, to add two interpolated files, Cell 1 
of input file A is added to Cell 1 of input file B and the sum is stored in Cell 1 of 
output file C, and so forth. Subtracting one file from another can be used to show 
change from one time to another (Figure D-14). Missing values are handled as in 
regular math—a non-missing value becomes missing if a math operation attempts to 
compare a real value with a missing value. Division by zero or other illegal math 
operation will cause the operation to stop. 
The “Derive New Parameter” math operations can be performed sequentially to 
provide additional capability. For instance, five interpolated files (.est files) could be 
sequentially added together, then the resulting file could be divided by 5 to compute 
appendix d 
User Guide and Documentation for the Chesapeake Bay Interpolator 
