This field comparator is for numeric fields, where a given maximal
percentage difference can be tolerated. This percentage has to be set
by the argument `max_perc_diff`

as a value between and
. The default value is , i.e. no difference is tolerated.

The agreement weight is returned if the numbers are the same, and the
disagreement weight if the percentage difference is larger than the
`max_perc_diff`

value. If the percentage difference between the
two values is larger than but equal to or smaller than
`max_perc_diff`

the partial agreement weight is calculated
according to the following formula.

where the percentage difference between the two values is calculated as

In its current version no frequency dependent weight calculation is
possible, thus the arguments `frequency_table`

,
`freq_table_max_weight`

and `freq_table_min_weight`

can not be used with this field comparator function.