excel - Combination of several INDEX and MATCH functions -

i'm working on evaluation excel sheet forceplate data (showing vertical force development in jumps on time) , stumbled upon problem couldn't manage fix past days. there 2 main columns on ~ 4000 rows , 1 cell:

column a shows time [in ms]

column b shows vertical force measured @ time point in column a

c1 calculated peak force value before takeoff

i trying define timepoint of takeoff in cell using index , match functions (fyi: time of takeoff when vertical force value close 0 first time [range of lookup must starting peak force value though!!], never 0 due force plate drift in measurement)

my idea this:

=index(a2:a4000;match(0;index(b2:b4000;match(c1;b2:b4000;0)):b4000;-1)) 

so range

index(b2:b4000;match(c1;b2:b4000;0)):b4000 

should define range of force values starting @ peak force value (c1).

unfortunately excel show me timepoint force value far away 0. i've tried same formula within easier (but purpose faulty) range (b2:b4000) , worked perfectly, guess problem i'm dealing lies somewhere within range defined index function. i'd glad if me out this!

you on right track. seems you've correctly adjusted range in nested index function match function retunr position within adjusted b2:b4000. need adjust a2:a4000 in same way position returned match correct.

=index(index(a2:a4000; match(c1; b2:b4000; 0)):a4000; match(0; index(b2:b4000; match(c1; b2:b4000; 0)):b4000; -1)) 

i don't have sample data test on believe correct.