07-Jan-2022 22:46:28

luhn_test():
  MATLAB/Octave version 9.8.0.1380330 (R2020a) Update 2
  Test luhn().

ch_is_digit_test():
  ch_is_digit() is TRUE if a character represents a digit.

   C      CH_IS_DIGIT(C)

  "0"            1
  "1"            1
  "2"            1
  "3"            1
  "4"            1
  "5"            1
  "6"            1
  "7"            1
  "8"            1
  "9"            1
  "X"            0
  "?"            0
  " "            0

ch_to_digit_test():
  ch_to_digit_test() converts character -> decimal digit

         1  "0"         0
         2  "1"         1
         3  "2"         2
         4  "3"         3
         5  "4"         4
         6  "5"         5
         7  "6"         6
         8  "7"         7
         9  "8"         8
        10  "9"         9
        11  "X"        -1
        12  "?"        -1
        13  " "        -1

s_digits_count_test():
  S_DIGITS_COUNT counts the digits in a string.

  We count 7 digits in "34E94-70.6"
  We count 0 digits in "Not a one!"
  We count 3 digits in "%8*k >>>> # SEVEN-0.3"

s_to_digits_test():
  S_TO_DIGITS: string -> digit vector

  Test string: "34E94-70.6"

  Extracted 5 digits:

     1:      3
     2:      4
     3:      9
     4:      4
     5:      7

  Test string: "34E94-70.6"

  Extracted 7 digits:

     1:      3
     2:      4
     3:      9
     4:      4
     5:      7
     6:      0
     7:      6

luhn_check_digit_calculate_test():
  LUHN_CHECK_DIGIT_CALCULATE calculates the check digit
  for a string of digits

  Check digit of "7992739871" is 3, expecting 3
  Check digit of "9876234510" is 0, expecting 0
  Check digit of "246897531" is 9, expecting 9
  Check digit of "135798642" is 9, expecting 9

luhn_is_valid_test():
  LUHN_IS_VALID determines whether a string with final
  Luhn check digit is valid.

  Validity of "79927398713" is 1, expecting 1
  Validity of "79924398713" is 0, expecting 0
  Validity of "79927398711" is 0, expecting 0

luhn_test():
  Normal end of execution.

07-Jan-2022 22:46:28