perform a calculation using logarithmic calculation
Gravity Form Calculation For Natural Logarithm
gform.addFilter('gform_calculation_result', function( result, formulaField, formId, calcObj ) {
if ( formId == '86' && formulaField.field_id == '3' ) {
var exponent = calcObj.replaceFieldTags( formId, '{:2}', formulaField ),
num = calcObj.replaceFieldTags( formId, '{:1}', formulaField );
result = Math.log( num );
}
return result;
} );