# Using the result of NonlinearSolve.jl allocates memory
**URL:** https://discourse.julialang.org/t/using-the-result-of-nonlinearsolve-jl-allocates-memory/131242
**Category:** Performance
**Tags:** nonlinearsolve
**Created:** [July 31, 2025, 8:46am UTC](https://discourse.julialang.org/t/using-the-result-of-nonlinearsolve-jl-allocates-memory/131242 "2025-07-31T08:46:47Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@Gako](https://discourse.julialang.org/u/Gako)
#### Post date: [July 31, 2025, 8:46am UTC](https://discourse.julialang.org/t/using-the-result-of-nonlinearsolve-jl-allocates-memory/131242/1 "2025-07-31T08:46:47Z")
I’m using the following code to try and understand how broadcasting and allocation work in Julia:
```julia
using NonlinearSolve
function nonlin()
nonlinprob(x, p) = return x - 3
prob = NonlinearProblem(nonlinprob, 2.)
sol = solve(prob, SimpleNewtonRaphson()).u
a = zeros(100)
b = range(1, 2, 100)
@time a .= sol
@time a .= sol .+ b
@time a .= sol .+ b.^2 .+ b.^3
@time a[1] = sol + b[1]^2
@time a[1] = sol
@time a .= 1.5 .+ b.^2 .+ b.^3
nothing
end
nonlin()
```
My (perhaps naïve) assumption was that none of these would allocate as nothing is created. However, the output is
```julia
0.000007 seconds (1 allocation: 16 bytes)
0.000006 seconds (2 allocations: 128 bytes)
0.000009 seconds (8 allocations: 416 bytes)
0.000006 seconds (1 allocation: 16 bytes)
0.000001 seconds
0.000000 seconds
```
meaning that only the last two don’t allocate. Now this lead me to believe that there might be some type instability with the extracted solution, but doing something like `a = zeros(eltype(sol), 100)` results in the same amount and size of allocations (apart from the last for which the allocations of course increase). Furthermore, `print(eltype(sol))` gives `Float64`, as expected. What could cause these allocations in this code?
---
### Author:  [@ChrisRackauckas](https://discourse.julialang.org/u/ChrisRackauckas)
#### Post date: [July 31, 2025, 9:45am UTC](https://discourse.julialang.org/t/using-the-result-of-nonlinearsolve-jl-allocates-memory/131242/2 "2025-07-31T09:45:32Z")
If you do `prob = NonlinearProblem{false}(nonlinprob, 2.)` is it fine?
---
### Author:  [@Gako](https://discourse.julialang.org/u/Gako)
#### Post date: [July 31, 2025, 9:52am UTC](https://discourse.julialang.org/t/using-the-result-of-nonlinearsolve-jl-allocates-memory/131242/3 "2025-07-31T09:52:45Z")
Yes, if I do that the allocations disappear. What does adding the {false} do if I may ask? Searching I see it in a few examples in the NonlinearSolve.jl FAQ but no explanation really.
---
### Author:  [@ChrisRackauckas](https://discourse.julialang.org/u/ChrisRackauckas)
#### Post date: [July 31, 2025, 10:41am UTC](https://discourse.julialang.org/t/using-the-result-of-nonlinearsolve-jl-allocates-memory/131242/4 "2025-07-31T10:41:09Z")
> [@Gako](#):
>
> What does adding the {false} do if I may ask?
Directly sets iip=false, i.e. out of place. That should be compiler inferred but something in the later versions seems to be going on. I need to handle that.