# Field Arithmetic

Submenu on "EDIT" button on database table form.  The button is only enabled if you check the box on the right of the row of buttons, since all changes are permanent (save a copy of the database if you are concerned about editing mistakes).

 Copy numeric field Sum 2 Fields-add a new field with the sum of two existing fields Difference 2 Fields--add a new field with the difference between two existing fields Multiply 2 Fields--add a new field by multiplying two existing fields Quotient 2 Fields (ratio)--add new field with the quotient of two existing fields.  If the divisor is 0, the result will be undefined. Percent field: pick a field, and it will be summed and for each record the percentage of the sum will be computed and added. The next options do not add a new field; if you want to keep the original field, copy the field first Add constant to field: pick a field, and add a constant to  all records (meeting the current filter).  Multiply field by constant: pick a field, and multiply all records (meeting the current filter) by a constant.  Divide field by constant: pick a field, and multiply all records (meeting the current filter) by a constant.  Fix compass angles: Insure all angles are in the 0-360 range Normalize fields--select fields will be scaled so that 0 is  mean of the original field, and values represent standard deviations from the mean.  This will create a new database. Log of Field--If the value is 0 or negative, the result will be undefined. Sin of Field--sine of field, interpreted in degrees. Cos of Field--cosine of field, interpreted in degrees. Average of neighbors--requires that the neighbors have been computed and stored,  and adds a new field with the average of their values. Sum of neighbors Mean Filter Field: pick the number of terms to use for the filter.  Records at the start and end will not be filtered. Median Filter Field: better removal of outliers compared to mean filter, since the outlier has no effect on the filtered value. Z statistics: z values of the first and last point in a line shapefile. Remove missing data Pick field All fields Oceanography-- requires that Oceanography options are enabled, and  fields TEMP_C and SALINITY and DEPTH exist; compute Sigma tee Sigma theta Sound velocity

Last revision 2/26/2021