# Improve performance of this index creation and accessing code

**URL:** <https://discourse.julialang.org/t/improve-performance-of-this-index-creation-and-accessing-code/134235>\
**Category:** Performance\
**Tags:** indexing, rounding\
**Created:** [November 30, 2025, 3:59pm UTC](https://discourse.julialang.org/t/improve-performance-of-this-index-creation-and-accessing-code/134235 "2025-11-30T15:59:23Z")\
**Posts on this page:** 1\
**Showing post:** 24

<div class="post-metadata">

**Author:** ![abraemer](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/abraemer/32/51403_2.png) [@abraemer](https://discourse.julialang.org/u/abraemer)\
**Post date:** [December 4, 2025, 9:52pm UTC](https://discourse.julialang.org/t/improve-performance-of-this-index-creation-and-accessing-code/134235/24 "2025-12-04T21:52:25Z")

</div>

> [@raman\_kumar](#):
>
> ```julia-auto
> function bound(xe_all, ye_all, ze_all, MeshBlockSize, blocks)
> XX,YY,ZZ = ntuple(_ -> zeros(Float32, blocks* prod(MeshBlockSize.+1)), 3)
> icx=1
> for b in 1:blocks
> @views r, θ, ϕ = xe_all[:, b], ye_all[:, b], ze_all[:, b]
> for rr in r, th in θ, ph in ϕ,  
> XX[icx] = rr * sin(th) * cos(ph)
> YY[icx] = rr * sin(th) * sin(ph)
> ZZ[icx] = rr * cos(th)
> icx += 1
> end
> end
> xmin,xmax = extrema(XX); ymin,ymax = extrema(YY); zmin,zmax = extrema(ZZ)
> println(" x ∈ [$xmin, $xmax], y ∈ [$ymin, $ymax], z ∈ [$zmin, $zmax]")
> return xmin, xmax, ymin, ymax, zmin, zmax
> end
> 
> ```

This function is very inefficient: you allocate a huge array only to get the extrema. Also since you take all combinations anyhow, you can extremize each axis by itself. Here is my suggestion which should take a fraction of the original runtime:

```julia-auto
function bound(xe_all, ye_all, ze_all)
    xmin = Inf; xmax = -Inf
    ymin = Inf; ymax = -Inf
    zmin = Inf; zmax = -Inf
    for block in axes(xe_all, 2)
        @views r, theta, phi = xe_all[:, b], ye_all[:, b], ze_all[:, b]
        rvals = extrema(r)
        theta_sin_vals = extrema(sin, theta)
        theta_cos_vals = extrema(cos, theta)
        phi_sin_vals = extrema(sin, phi)
        phi_cos_vals = extrema(cos, phi)
        
        new_zmin, new_zmax = extrema(r*cos_theta for r in rvals for cos_theta in theta_cos_vals)
        zmax = max(zmax, new_zmax)
        zmin = min(zmin, new_zmin)
        # do the others yourself
    end
    return xmin, xmax, ymin, ymax, zmin, zmax
end

```

> [@raman\_kumar](#):
>
> ```julia-auto
> @inbounds for ii in 1:nr, jj in 1:nθ, kk in 1:nϕ
> cart(iex,ii,jj,kk,r_eval,θ_eval,ϕ_eval,ext_itp,X,Y,Z,C)
> clp(X[iex],Y[iex],Z[iex],C[iex],xmin,ymin,zmin,sx,sy,sz,nx,ny,nz,field)
> iex += 1
> end
> 
> ```

Note that the `xmin`, `ymin`, `zmin` parameters are globals again. In this inner loop that will cost a lot of performance.

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