I have a simple program using the time() function and can’t understand the results the time() function is giving. My guess is it has something to do with Julia’s optimization. I expect that two different calls to time() would report the elapsed time taken by two nested loops; but the reported time difference is 0.0. The function is:

```
function shrtTm(cnt)
t1 = time()
a = 0
b = 0
for i = 1:cnt
a +=1
for j = 1:8000
b +=1
end
end
t2 = time()
deltT = t2-t1
println(@sprintf("t1: %.12f, t2:%.12f, diff: %.12f, a: %u, b: %u", t1, t2, deltT, a, b))
deltT, b
end
```

When I run it using BenchmarkTools (without using BenchmarkTools, I get similar results), I get:

```
julia> b = @benchmarkable shrtTm(1000000000000) samples=10
Benchmark(evals=1, seconds=5.0, samples=10)
julia> run(b)
t1: 1586091074.023055076599, t2:1586091074.023055076599, diff: 0.000000000000, a: 1000000000000, b: 8000000000000000
t1: 1586091074.023112058640, t2:1586091074.023112058640, diff: 0.000000000000, a: 1000000000000, b: 8000000000000000
t1: 1586091074.023137092590, t2:1586091074.023137092590, diff: 0.000000000000, a: 1000000000000, b: 8000000000000000
t1: 1586091074.023149013519, t2:1586091074.023149013519, diff: 0.000000000000, a: 1000000000000, b: 8000000000000000
t1: 1586091074.023161888123, t2:1586091074.023161888123, diff: 0.000000000000, a: 1000000000000, b: 8000000000000000
t1: 1586091074.023174047470, t2:1586091074.023174047470, diff: 0.000000000000, a: 1000000000000, b: 8000000000000000
t1: 1586091074.023190021515, t2:1586091074.023190021515, diff: 0.000000000000, a: 1000000000000, b: 8000000000000000
t1: 1586091074.023212909698, t2:1586091074.023212909698, diff: 0.000000000000, a: 1000000000000, b: 8000000000000000
t1: 1586091074.023232936859, t2:1586091074.023232936859, diff: 0.000000000000, a: 1000000000000, b: 8000000000000000
t1: 1586091074.023252010345, t2:1586091074.023252010345, diff: 0.000000000000, a: 1000000000000, b: 8000000000000000
BenchmarkTools.Trial:
memory estimate: 592 bytes
allocs estimate: 10
--------------
minimum time: 10.797 μs (0.00% GC)
median time: 16.431 μs (0.00% GC)
mean time: 19.046 μs (0.00% GC)
maximum time: 48.915 μs (0.00% GC)
--------------
samples: 10
evals/sample: 1
julia> (1586091074.023252010345 - 1586091074.023055076599)/10
1.969337463378906e-5
julia>
```

The function is taking about 20us each time it runs, and this agrees with the absolute times t1 and t2 as seen by the last line, but what I can’t understand is why the reported deltT as in:

```
julia> deltT, b = shrtTm(1000000000000)
t1: 1586091612.786988973618, t2:1586091612.786988973618, diff: 0.000000000000, a: 1000000000000, b: 8000000000000000
(0.0, 8000000000000000)
julia>
```

is being reported as 0.0 time. I would have thought it would report the time taken by the loops. The loops are certainly occurring as changing the argument changes the reported values for a and b.

```
julia> deltT, b = shrtTm(200)
t1: 1586091753.394443035126, t2:1586091753.394443035126, diff: 0.000000000000, a: 200, b: 1600000
(0.0, 1600000)
julia>
```