
Converting an ILS Localiser Simulator from 1980’s Turbo Basic to Java - martinfjohansen
https://www.progsbase.com/blog/industrial-case-converting-an-ils-localiser-simulator-from-1980s-turbo-basic-to-java/
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ptx
Sound neat. But I wonder about those "quality assured computations that have
been used and tested through many years" \- when they convert the source code
to a different language, using a brand new converter + a reimplemented
standard library + 5% manual editing, how can they be sure the computations
are still correct? Especially since they mention that the results are
different due to 64-bit precision.

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martinfjohansen
Those are good questions, I should have written more about that in the
article! I'll give some brief answers:

Regarding the age of the converter: Even though it is new it is thought
through. Check out the detailed documentation and technical articles on the
website for an explanation. The converter basically deals with floating point
computations carefully and in a way programmers commonly deal with them when
doing scientific computations.

The reimplemented standard library are methods such as draw a line from point
a to b, or draw this text at this point. Draw pixels at a certain coordinate,
check if a key was pressed. So, the basic answer is that the functions were
quite simple to get right. Had the library been more complicated, it would
have been a different story.

Yes, you are right about the 5% edits. I should have added a section on Q&A
done after the translation was done. It is of course very important to test
code carefully after translation.

