Thank you very much ! I give you the results :
my loop solution : 0.000419 seconds (547 allocations: 708.797 KB) 0.02000000000000135 -> 73 @time closest_index(x,8.22) 0.000003 seconds (4 allocations: 160 bytes) 73 @time for (i,x) in enumerate(array)... 0.000181 seconds (821 allocations: 19.953 KB) 738.20.02000000000000135 @time reduce((x,y)->x[2]<y[2]?x:y,(0,1000),map((x,y)->(x,abs(y-8.22)),1:length(x),x)) 0.005890 seconds (892 allocations: 24.617 KB) Of course in my particular situation the array is sorted, so in that case I although think about using dichotomy
