Hello everyone,

The title is surely a bit misleading, but it's also the title of a YT video,
so I adopted it for this thread, as well. I hope yo don't mind.

Long story short, it's about how a missle calculates its position.
Or at least how it did in the 1960s..

Long story: It's a wonderful example of how something truely bizarre can make sense.
Also, the English wording is pure art, I think. 🤣
It's as if the poor thing has to go through a mental crisis..

Here it goes:

"The missile knows where it is at all times.
It knows this because it knows where it isn't.
By subtracting where it is from where it isn't, or where it isn't from where it is,
whichever is greater, it obtains a difference or deviation.

The guidance subsystem uses deviations to generate corrective commands to drive the missile
from a position where it is, to a position where it isn't, and arriving at
a position where it wasn't, it now is.

Consequently the position where it is is now the position that it wasn't,
that it follows that the position that it was is now the position that it isn't.
In the event that the position that it is in is not the position that it wasn't,
the system has acquired a variation.

The variation being the difference between where the missile is, and where it wasn't.
If variation is considered to be a significant factor it too may be corrected by the GEA.
However, the missile must also know where it was.

The missile guidance computer scenario works as follows;
because the variation has modified some of the information the missile has obtained,
it is not sure just where it is, however it is sure where it isn't within reason and knows where it was.
It now subtracts where it should be from where it wasn't or vice versa, and by differentiating this from
the algebraic sum of where it shouldn't be, and where it was, it is able to obtain
the deviation and its variation which is called error."

Source with English narration:
https://youtu.be/bZe5J8SVCYQ

(It get's easier if you think of a source, a destination and a flight path or vector.)

Anyway, I hope you enjoy this one as much as I did. 😄

Best regards,
Jo22