The UDEC function returns a character-string value that  is  the
  unsigned  decimal  equivalent  of  the specified parameter.  The
  return value is compatible with all other string types.

  Syntax:

     UDEC(x [[,length[[,digits]]]])

  The parameter 'x' is the expression to be converted.   The  UDEC
  function  can  take  a  parameter  of any type except VARYING OF
  CHAR, conformant parameters, or  schema  types.   This  function
  requires the size of 'x' to be less than or equal to the size of
  INTEGER64 (if supported) on your system.  If  your  system  does
  not  support INTEGER64, then the UDEC function requires that 'x'
  be less than or equal to the size of INTEGER32.

  Two optional  integer  parameters  specify  the  length  of  the
  resulting string and the minimum number of significant digits to
  be returned.  If you specify a length that is too short to  hold
  the  converted  value,  the resulting string is truncated on the
  left.

  If you do not specify values  for  the  optional  parameters,  a
  default  length  and  a  default  minimum  number of significant
  digits is used.  If the size of 'x'  is  greater  than  32,  the
  defaults  are 21 characters for the length and 20 characters for
  the minimum number of digits.  Otherwise, the  defaults  are  11
  characters  for  the  length  and  10 characters for the minimum
  number of digits.