"JE McGimpsey" ha scritto nel messaggio
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One way:

If E1 is in column A:

=MATCH(1,A:A,TRUE)


No sure I understand your last criterion. Is it guaranteed that there
will be an i for which (i-1)<1 and (i+1)1? In other words, is it
possible that you could have something like

0,8; 0,9; 1,0; 1,0; 1,1

for which there is no solution?

thank you for your answer.
IT isn't possible, they are increasing values (and positive,too) each one
smaller than its follower