Tuflow and estry manual Version 3

8.4Why Do I Get Different Results?

Hopefully, this never occurs! However, like most (all?) computational software, providing backward compatibility (ie. getting the same results with different versions of the software) is at times very difficult. This is mainly associated with complications in the code when making improvements and, of course, the occasional bug. They can even be due to vagaries of the source code compiler (as has been found with immense frustration on several occasions!).

During the life of TUFLOW since 1989, every effort has been made to provide full backward compatibility. Models developed back then can still be simulated to achieve the same results. Old file formats are still recognised or can be translated into more recent formats. There have, however, been numerous enhancements, improvements and the inevitable bug fixes. Models using some of these new features during the development stages may produce slightly different results using latter versions of the software.

Since March 2001, a unique software build identifier has been used to track and manage new versions of the software. The build number is in the format of year-month-xx where xx is two letters starting at AA then AB, AC, etc for each new build for that month. The build number is written to the first line in the .elf and .tlf log files so that it is clear what version of the software was used to simulate the model.

Table 9 .34 presents known possible changes that may affect model results. In all cases the changes are considered to be minimal, and are likely to affect relatively few, if any, models.

Table 9.34 Possible Reasons for Different Results in Reverse Chronological Order