Software Venture Consulting

FileMaker Pro downloads & Resources
FileMaker Custom Functions
FileMaker Web Viewer Examples
FileMaker Pro & Lasso Consulting
Training
FileMaker Books
FileMaker Articles
FileMaker Error Reference

Free Web Tools
Free FileMaker Tools

Personal Pages
Videos
Adventures
Links

Shopping Cart
Shopping Cart

Search:

Free Newsletter
Signup


Contact


Privacy Policy



FileMaker is a registered trademark of FileMaker, Inc. in the U.S. and other countries.

 

 FileMaker Pro Custom Functions

List  |  Show Random  |  Upload  |  Add This to Your Site

CheckdigitDamm ( digitSequence )

Rate this function:  

RatingRatingRatingRatingRating
  Average rating: 4.9  (23 votes)
  Discuss this Custom Function

Jeremy Bante, Beezwax Datatools, Inc.
http://beezwax.net

Calculates a check digit using the Damm algorithm

Sample Input:
List (
CheckdigitDamm ( 12345 ) ;
12345 & CheckdigitDamm ( 12345 ) ;
CheckdigitDamm ( 12345 & CheckdigitDamm ( 12345 ) )
)
Sample Output:
9
123459
0


 Then copy & paste into FileMaker Advanced's Edit Custom Function window.

Click here to copy To Clip Manager if you have myFMbutler's Clip Manager installed

Description:

Calculates a check digit to append to a digit sequence that can be used to validate that the digit sequence has been transcribed correctly.

This custom function implements an algorithm described by H. Michael Damm in 2004.

Note: these functions are not guaranteed or supported by BrianDunning.com. Please contact the individual developer with any questions or problems.

This is my Custom Function and I want to edit it

Discuss:

Excellent! The Damm algorithm is, AFAIK, the most robust one out there for a single-numeric-digit check digit scheme. It's able to detect all single-digit transcription errors (e.g., 6↔9) and all adjacent transpositions (e.g., 47↔74)—which together account for 90% of errors—and most (though not all) of the other common errors, such as jump transpositions (e.g., 358↔853), twin errors (e.g., 44↔66), and jump twins (e.g., 494↔797). Additionally, it detects all English-language phonetic errors (e.g., 16↔60).

The older and more widely known Luhn algorithm misses the transposition 09↔90—yikes! those digits are right next to one another on any keyboard without a dedicated numeric keypad (think laptop!)—as well as the twin errors 22↔55, 33↔66, and 44↔77. Yikes, again! Those three pairs are each vertically adjacent on a numeric keypad.

I was about to code this myself, then decided to check here to see if someone has saved me from reinventing the wheel. Thanks, Jeremy; good work!

Mark

Mark Scott, San Francisco
January 09, 2015 12:53pm

Make a comment about this Custom Function (please try to keep it brief & to the point). Anyone can post:

Your Name:
City/Location:
Comment:
characters left. If you paste in more than 1500 characters, it will be truncated. Discuss the function - advertisements and other useless posts will be deleted.
Answer 8 + 7 =
Search for Custom Functions:

Custom Functions Widget
Download the Custom Function Dashboard Widget for OS X
Keep all the latest Custom Functions right at your fingertips!

Newest Custom Functions:

1. NumberToHexadecimal(NumberValue)
  (Fri, Dec 08, 8:54am)
2. Get_BaseTable
  (Thu, Dec 07, 4:27pm)
3. JSONCreateVarsFromKeys ( json ; namespace )
  (Wed, Dec 06, 8:21pm)
4. GetTableNzme ( field )
  (Tue, Dec 05, 9:16pm)
5. TimeFormatAsText ( theTime )
  (Mon, Nov 13, 1:59pm)
6. ParseWebValueList( text )
  (Thu, Nov 02, 9:52am)
7. SVG_HTML_to_Text ( _svg_text ; _orig_text ;
  (Wed, Oct 25, 4:17am)
8. decFromHex ( hexValue )
  (Mon, Oct 16, 12:34pm)

RSS Feed of Custom Functions