# @btime inside function

**URL:** https://discourse.julialang.org/t/btime-inside-function/108773
**Category:** General Usage
**Created:** [January 13, 2024, 3:13pm UTC](https://discourse.julialang.org/t/btime-inside-function/108773 "2024-01-13T15:13:04Z")
**Posts on this page:** 3
**Page:** 1

<div class="post-metadata">

### Author: ![scheinerman](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/scheinerman/32/35303_2.png) [@scheinerman](https://discourse.julialang.org/u/scheinerman)
#### Post date: [January 13, 2024, 3:13pm UTC](https://discourse.julialang.org/t/btime-inside-function/108773/1 "2024-01-13T15:13:04Z")

</div>

I would like to create a function to time test various operations, but it seems that invoking `@btime` (from `BenchmarkTools`) doesn’t work in this situation. Is there a way to use `@btime` inside a function. (Note: `@time` works.)

For example:

```julia
using BenchmarkTools

function mult_time_1(n=100)
    A = rand(n,n)
    @time A^2
    nothing
end

function mult_time_2(n=100)
    A = rand(n,n)
    @btime A^2
    nothing
end

```

In this example, `mult_time_1` works fine, but `mult_time_2` gives the following error:

```julia
julia> mult_time_2()
ERROR: UndefVarError: `A` not defined
Stacktrace:
  [1] var"##core#262"()
    @ Main ~/.julia/packages/BenchmarkTools/QAv7m/src/execution.jl:547
  [2] var"##sample#263"(::Tuple{}, __params::BenchmarkTools.Parameters)
    @ Main ~/.julia/packages/BenchmarkTools/QAv7m/src/execution.jl:556
  [3] _run(b::BenchmarkTools.Benchmark, p::BenchmarkTools.Parameters; verbose::Bool, pad::String, kwargs::@Kwargs{…})
    @ BenchmarkTools ~/.julia/packages/BenchmarkTools/QAv7m/src/execution.jl:109
  [4] #invokelatest#2
    @ ./essentials.jl:889 [inlined]
  [5] invokelatest
    @ ./essentials.jl:884 [inlined]
  [6] #run_result#45
    @ ~/.julia/packages/BenchmarkTools/QAv7m/src/execution.jl:41 [inlined]
  [7] run_result
    @ ~/.julia/packages/BenchmarkTools/QAv7m/src/execution.jl:40 [inlined]
  [8] run(b::BenchmarkTools.Benchmark, p::BenchmarkTools.Parameters; progressid::Nothing, nleaves::Float64, ndone::Float64, kwargs::@Kwargs{…})
    @ BenchmarkTools ~/.julia/packages/BenchmarkTools/QAv7m/src/execution.jl:134
  [9] run (repeats 2 times)
    @ BenchmarkTools ~/.julia/packages/BenchmarkTools/QAv7m/src/execution.jl:126 [inlined]
 [10] #warmup#54
    @ BenchmarkTools ~/.julia/packages/BenchmarkTools/QAv7m/src/execution.jl:189 [inlined]
 [11] warmup(item::BenchmarkTools.Benchmark)
    @ BenchmarkTools ~/.julia/packages/BenchmarkTools/QAv7m/src/execution.jl:188
 [12] macro expansion
    @ ~/.julia/packages/BenchmarkTools/QAv7m/src/execution.jl:652 [inlined]
 [13] mult_time_2(n::Int64)
    @ Main ~/.julia/dev/MiniMods/test/test_test.jl:12
 [14] mult_time_2()
    @ Main ~/.julia/dev/MiniMods/test/test_test.jl:11
 [15] top-level scope
    @ REPL[11]:1

```

---

<div class="post-metadata">

### Author: ![ejmeitz](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/ejmeitz/32/45283_2.png) [@ejmeitz](https://discourse.julialang.org/u/ejmeitz)
#### Post date: [January 13, 2024, 3:49pm UTC](https://discourse.julialang.org/t/btime-inside-function/108773/2 "2024-01-13T15:49:30Z")

</div>

You can interpolate A into the expression.

```juli
function mult_time_2(n=100)
    A = rand(n,n)
    @btime ($A)^2
    nothing
end

```

---

<div class="post-metadata">

### Author: ![scheinerman](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/scheinerman/32/35303_2.png) [@scheinerman](https://discourse.julialang.org/u/scheinerman)
#### Post date: [January 13, 2024, 3:51pm UTC](https://discourse.julialang.org/t/btime-inside-function/108773/3 "2024-01-13T15:51:03Z")

</div>

> [@ejmeitz](#):
>
> ```julia
> function mult_time_2(n=100)
> A = rand(n,n)
> @btime ($A)^2
> nothing
> end
> 
> ```

Thanks!