On 2017-01-30 21:39, Tom Van Baak wrote:
2017-01-01T00:00:35.5 TAI = 2016-12-31T23:59:59.5 UTC
I do have problems with your notation.
You apparently want to say that
"whenever TAI assumes the value 2017-01-01T00:00:35.5,
then UTC assumes the value 2016-12-31T23:59:59.5"
but I do not see which two things are denoted by the two
members of your equation, and are supposed to be equal.
If the value of the left member is the set
{ X : TAI( X ) = 2017-01-01T00:00:35.5 }
of all points X in spacetime where TAI assumes the value
2017-01-01T00:00:35.5, and similarly for the right member,
then in fact you would have a correct equation.
But the notation
2017-01-01T00:00:35.5 TAI
normally is not taken to mean a set of points in
spacetime, but the epoch 2017-01-01T00:00:35.5
with the additional information that it is a value of
the TAI time scale.
2017-01-01T00:00:35.5 TAI - 36 s = 2016-12-31T23:59:59.5 UTC
I am completely lost here. If your first equation was
A = B, then you are now saying A - 36 s = B. I cannot
make sense out of it.
If you mean
2017-01-01T00:00:35.5 - 36 s = 2016-12-31T23:59:59.5
then why not say it?
My original point was that your arithmetic on datetimes
was confused. If the additive group of time values operates
on datetimes in the usual manner, then
2017-01-01T00:00:00.5
= 2017-01-01T00:00:00.5 + 0 s
= 2017-01-01T00:00:00.5 + (36 s - 36 s)
= (2017-01-01T00:00:00.5 + 36 s) - 36 s
= 2017-01-01T00:00:36.5 - 36 s
= "2016-12-31T23:59:60.5" in your notation
as I claimed. But possibly you do not want to use
the usual operation of the group of time values on
datetimes. I cannot reasonably comment on your posts
it unless you specify rigorously which operations
you mean.
Michael Deckers.
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