# History of \`isapprox\` in languages

**URL:** <https://discourse.julialang.org/t/history-of-isapprox-in-languages/119347>\
**Category:** Numerics\
**Tags:** question, numerics, approx\
**Created:** [September 12, 2024, 6:51pm UTC](https://discourse.julialang.org/t/history-of-isapprox-in-languages/119347 "2024-09-12T18:51:09Z")\
**Posts on this page:** 1\
**Showing post:** 3

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**Author:** ![zdenek\_hurak](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/zdenek_hurak/32/53118_2.png) [@zdenek\_hurak](https://discourse.julialang.org/u/zdenek_hurak)\
**Post date:** [September 12, 2024, 7:26pm UTC](https://discourse.julialang.org/t/history-of-isapprox-in-languages/119347/3 "2024-09-12T19:26:24Z")

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> [@Bug with isapprox?](https://discourse.julialang.org/t/bug-with-isapprox/7600/5):
>
> This has nothing to do with the value of eps(0.0). x ≈ 0.0 will always give false for x ≠ 0, because ≈ tests only relative error. If x ≠ 0, then no significant digits of x match 0.0, so the result of x ≈ 0.0 is false. In particular, x ≈ y tests norm(x-y) ≤ sqrt(eps(T))\*max(norm(x),norm(y)) with T=typeof(real(x-y)), which tests whether about half of the significant digits match. If you call isapprox(x,y) explicitly, you can pass an atol argument to instead pass an absolute tolerance, i.e. t…

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