# Fastest way to check for Inf or NaN in an array?

**URL:** https://discourse.julialang.org/t/fastest-way-to-check-for-inf-or-nan-in-an-array/76954
**Category:** General Usage
**Tags:** question, performance, arrays
**Created:** [February 23, 2022, 5:04am UTC](https://discourse.julialang.org/t/fastest-way-to-check-for-inf-or-nan-in-an-array/76954 "2022-02-23T05:04:30Z")
**Posts on this page:** 1
**Showing post:** 20

<div class="post-metadata">

### Author: ![Oscar\_Smith](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/oscar_smith/32/25343_2.png) [@Oscar\_Smith](https://discourse.julialang.org/u/Oscar_Smith)
#### Post date: [February 23, 2022, 5:59am UTC](https://discourse.julialang.org/t/fastest-way-to-check-for-inf-or-nan-in-an-array/76954/20 "2022-02-23T05:59:53Z")

</div>

Here is the absolute fastest version. It uses a combination of early exits and vectorization to get maximum performance.

```julia
function y(x)
    for i in firstindex(x):64:(lastindex(x)-63)
        s = zero(eltype(x))
        @turbo for j in 0:63
            s += x[i+j]*0
        end
        !isfinite(s) && return false
        end
    return all(isfinite, @view x[max(end-64,begin):end])
end

```

(for sparse arrays, you want to do the same thing, but on `nonzeros(x)` instead of `x`)

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