# Why is \`fld1\` not named \`cld1\`?

**URL:** <https://discourse.julialang.org/t/why-is-fld1-not-named-cld1/138317>\
**Category:** General Usage\
**Tags:** question, math\
**Created:** [July 17, 2026, 12:42pm UTC](https://discourse.julialang.org/t/why-is-fld1-not-named-cld1/138317 "2026-07-17T12:42:30Z")\
**Posts on this page:** 6\
**Page:** 1

<div class="post-metadata">

**Author:** ![rokke](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/rokke/32/222691_2.png) [@rokke](https://discourse.julialang.org/u/rokke)\
**Post date:** [July 17, 2026, 12:42pm UTC](https://discourse.julialang.org/t/why-is-fld1-not-named-cld1/138317/1 "2026-07-17T12:42:30Z")

</div>

question in title; `fld1` seems much more similar to `cld` than `fld`:

```julia-auto
julia> findall(!iszero, [fld1(a,b)-cld(a,b) for a=-10000:.1:10000, b=[-100:-1; 1:100]]) |> length
0

julia> findall(!iszero, [fld1(a,b)-fld(a,b) for a=-10000:.1:10000, b=[-100:-1; 1:100]]) |> length
39792664 

```

it only seems to match `fld` when you’re specifically looking for floating pointy weirdness:

```julia-auto
julia> fld1(3, 0.3)
10.0

julia> cld(3, 0.3)
11.0

julia> fld(3, 0.3)
10.0

```

actually, the code for integers appears to be identical, since `(0<a) == (0<b)` is the same as `(a⊻b) >= 0` for non-zero a & b:

```julia-auto
julia> @code_typed fld1(20,3)
CodeInfo(
1 ─ %1 = intrinsic Base.checked_sdiv_int(x, y)::Int64
│ %2 = intrinsic Base.xor_int(x, y)::Int64
│ %3 = intrinsic Base.slt_int(%2, 0)::Bool
│ %4 = intrinsic Base.not_int(%3)::Bool
│ %5 = intrinsic Base.mul_int(%1, y)::Int64
│ %6 = builtin (%5 === x)::Bool
│ %7 = intrinsic Base.not_int(%6)::Bool
│ %8 = intrinsic Base.and_int(%4, %7)::Bool
│ %9 = intrinsic Core.zext_int(Core.Int64, %8)::Int64
│ %10 = intrinsic Core.and_int(%9, 1)::Int64
│ %11 = intrinsic Base.add_int(%1, %10)::Int64
└── return %11
) => Int64

julia> @code_typed cld(20,3)
CodeInfo(
1 ─ %1 = intrinsic Base.checked_sdiv_int(a, b)::Int64
│ %2 = intrinsic Base.slt_int(0, a)::Bool
│ %3 = intrinsic Base.slt_int(0, b)::Bool
│ %4 = builtin (%2 === %3)::Bool
│ %5 = intrinsic Base.mul_int(%1, b)::Int64
│ %6 = builtin (%5 === a)::Bool
│ %7 = intrinsic Base.not_int(%6)::Bool
│ %8 = intrinsic Base.and_int(%4, %7)::Bool
│ %9 = intrinsic Core.zext_int(Core.Int64, %8)::Int64
│ %10 = intrinsic Core.and_int(%9, 1)::Int64
│ %11 = intrinsic Base.add_int(%1, %10)::Int64
└── return %11
) => Int64

```

it seems like it would make more sense to call something that’s pretty much `cld` as `cld1`, not `fld1`. is there some theory reason it’s called `fld1`?

---

<div class="post-metadata">

**Author:** ![GunnarFarneback](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/gunnarfarneback/32/1827_2.png) [@GunnarFarneback](https://discourse.julialang.org/u/GunnarFarneback)\
**Post date:** [July 17, 2026, 1:23pm UTC](https://discourse.julialang.org/t/why-is-fld1-not-named-cld1/138317/2 "2026-07-17T13:23:29Z")

</div>

I’ll leave a longer explanation to someone with more time but the short answer is given in its docstring:

```julia-auto
  Flooring division, returning a value consistent with mod1(x,y)

```

---

<div class="post-metadata">

**Author:** ![rokke](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/rokke/32/222691_2.png) [@rokke](https://discourse.julialang.org/u/rokke)\
**Post date:** [July 17, 2026, 1:28pm UTC](https://discourse.julialang.org/t/why-is-fld1-not-named-cld1/138317/3 "2026-07-17T13:28:21Z")

</div>

but couldn’t that just as easily have been written `ceiling division, returning a value consistent with mod1(x,y)`? it seems to basically always be the ceiling, not the floor; the doc is just saying that its behavior is defined in terms of `mod1` rather than in terms of either `cld` or `fld`

---

<div class="post-metadata">

**Author:** ![Benny](https://avatars.discourse-cdn.com/v4/letter/b/49beb7/32.png) [@Benny](https://discourse.julialang.org/u/Benny)\
**Post date:** [July 17, 2026, 9:33pm UTC](https://discourse.julialang.org/t/why-is-fld1-not-named-cld1/138317/4 "2026-07-17T21:33:22Z")

</div>

> [@rokke](#):
>
> the doc is just saying that its behavior is defined in terms of `mod1`

And not in the manner that relates `fld` and `mod`, as the docstring examples imply:

```julia-auto
  julia> x == fld(x, y) * y + mod(x, y)
  true

  julia> x == (fld1(x, y) - 1) * y + mod1(x, y)
  true

```

which only seems even more similar to `cld` in many cases.

Relevant, though some behavior has been patched since: [fld1: unclear definition and seems broken for non-integers · Issue #14487 · JuliaLang/julia](https://github.com/JuliaLang/julia/issues/14487)

---

<div class="post-metadata">

**Author:** ![rokke](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/rokke/32/222691_2.png) [@rokke](https://discourse.julialang.org/u/rokke)\
**Post date:** [July 17, 2026, 10:02pm UTC](https://discourse.julialang.org/t/why-is-fld1-not-named-cld1/138317/5 "2026-07-17T22:02:09Z")

</div>

now I’m even more confused. I had kinda assumed that the equation listed in the docs was its defining property, but that appears to be only true for integer denominators. it seems to be one off about half the time?

```julia-auto
julia> [(x-mod1(x, y))/y + 1 - fld1(x,y) for x=-1000:.1:1000, y=[-100:.1:-1.; 1:.1:100]]
20001×1982 Matrix{Float64}:
 0.0 0.0 1.0 0.0 1.0 0.0 0.0 1.0 0.0 1.0 0.0 0.0 1.0 … 1.0 1.0 0.0 0.0 0.0 1.0 1.0 0.0 0.0 0.0 1.0 1.0 0.0
 0.0 0.0 1.0 0.0 1.0 0.0 0.0 1.0 0.0 1.0 0.0 0.0 1.0 1.0 1.0 0.0 0.0 0.0 1.0 1.0 0.0 0.0 0.0 1.0 1.0 0.0
 0.0 0.0 1.0 0.0 1.0 0.0 0.0 1.0 0.0 1.0 0.0 0.0 1.0 1.0 1.0 0.0 0.0 0.0 1.0 1.0 0.0 0.0 0.0 1.0 1.0 0.0
 0.0 0.0 1.0 0.0 1.0 0.0 0.0 1.0 0.0 1.0 0.0 0.0 1.0 1.0 1.0 0.0 0.0 0.0 1.0 1.0 0.0 0.0 0.0 1.0 1.0 0.0
 0.0 0.0 1.0 0.0 1.0 0.0 0.0 1.0 0.0 1.0 0.0 0.0 1.0 1.0 1.0 0.0 0.0 0.0 1.0 1.0 0.0 0.0 0.0 1.0 1.0 0.0
 0.0 0.0 1.0 0.0 1.0 0.0 0.0 1.0 0.0 1.0 0.0 0.0 1.0 … 1.0 1.0 0.0 0.0 0.0 1.0 1.0 0.0 0.0 0.0 1.0 1.0 0.0
 0.0 0.0 1.0 0.0 1.0 0.0 0.0 1.0 0.0 1.0 0.0 0.0 1.0 1.0 1.0 0.0 0.0 0.0 1.0 1.0 0.0 0.0 0.0 1.0 1.0 0.0
 0.0 0.0 1.0 0.0 1.0 0.0 0.0 1.0 0.0 1.0 0.0 0.0 1.0 1.0 1.0 0.0 0.0 0.0 1.0 1.0 0.0 0.0 0.0 1.0 1.0 0.0
 0.0 0.0 1.0 0.0 1.0 0.0 0.0 1.0 0.0 1.0 0.0 0.0 1.0 1.0 1.0 0.0 0.0 0.0 1.0 1.0 0.0 0.0 0.0 1.0 1.0 0.0
 0.0 0.0 1.0 0.0 1.0 0.0 0.0 1.0 0.0 1.0 0.0 0.0 1.0 1.0 1.0 0.0 0.0 0.0 1.0 1.0 0.0 0.0 0.0 1.0 1.0 0.0
 0.0 1.0 1.0 0.0 1.0 0.0 0.0 1.0 0.0 1.0 0.0 0.0 1.0 … 1.0 1.0 0.0 0.0 0.0 1.0 1.0 0.0 0.0 0.0 1.0 0.0 0.0
 0.0 1.0 1.0 0.0 1.0 0.0 0.0 1.0 0.0 1.0 0.0 0.0 1.0 1.0 1.0 0.0 0.0 0.0 1.0 1.0 0.0 0.0 0.0 1.0 0.0 0.0
 0.0 1.0 1.0 0.0 1.0 0.0 0.0 1.0 0.0 1.0 0.0 0.0 1.0 1.0 1.0 0.0 0.0 0.0 1.0 1.0 0.0 0.0 0.0 1.0 0.0 0.0
 0.0 1.0 1.0 0.0 1.0 0.0 0.0 1.0 0.0 1.0 0.0 0.0 1.0 1.0 1.0 0.0 0.0 0.0 1.0 1.0 0.0 0.0 0.0 1.0 0.0 0.0
 0.0 1.0 1.0 0.0 1.0 0.0 0.0 1.0 0.0 1.0 0.0 0.0 1.0 1.0 1.0 0.0 0.0 0.0 1.0 1.0 0.0 0.0 0.0 1.0 0.0 0.0
 0.0 1.0 1.0 0.0 1.0 0.0 0.0 1.0 0.0 1.0 0.0 0.0 1.0 … 1.0 1.0 0.0 0.0 0.0 1.0 1.0 0.0 0.0 0.0 1.0 0.0 0.0
 0.0 1.0 1.0 0.0 1.0 0.0 0.0 1.0 0.0 1.0 0.0 0.0 1.0 1.0 1.0 0.0 0.0 0.0 1.0 1.0 0.0 0.0 0.0 1.0 0.0 0.0
 0.0 1.0 1.0 0.0 1.0 0.0 0.0 1.0 0.0 1.0 0.0 0.0 1.0 1.0 1.0 0.0 0.0 0.0 1.0 1.0 0.0 0.0 0.0 1.0 0.0 0.0
 0.0 1.0 1.0 0.0 1.0 0.0 0.0 1.0 0.0 1.0 0.0 0.0 1.0 1.0 1.0 0.0 0.0 0.0 1.0 1.0 0.0 0.0 0.0 1.0 0.0 0.0
 ⋮ ⋮ ⋮ ⋱ ⋮ ⋮ ⋮
 0.0 0.0 1.0 0.0 0.0 0.0 1.0 1.0 0.0 0.0 0.0 1.0 1.0 1.0 0.0 0.0 1.0 0.0 1.0 0.0 0.0 1.0 0.0 1.0 1.0 0.0
 0.0 0.0 1.0 0.0 0.0 0.0 1.0 1.0 0.0 0.0 0.0 1.0 1.0 1.0 0.0 0.0 1.0 0.0 1.0 0.0 0.0 1.0 0.0 1.0 1.0 0.0
 0.0 0.0 1.0 0.0 0.0 0.0 1.0 1.0 0.0 0.0 0.0 1.0 1.0 … 1.0 0.0 0.0 1.0 0.0 1.0 0.0 0.0 1.0 0.0 1.0 1.0 0.0
 0.0 0.0 1.0 0.0 0.0 0.0 1.0 1.0 0.0 0.0 0.0 1.0 1.0 1.0 0.0 0.0 1.0 0.0 1.0 0.0 0.0 1.0 0.0 1.0 1.0 0.0
 0.0 0.0 1.0 0.0 0.0 0.0 1.0 1.0 0.0 0.0 0.0 1.0 1.0 1.0 0.0 0.0 1.0 0.0 1.0 0.0 0.0 1.0 0.0 1.0 1.0 0.0
 0.0 0.0 1.0 0.0 0.0 0.0 1.0 1.0 0.0 0.0 0.0 1.0 1.0 1.0 0.0 0.0 1.0 0.0 1.0 0.0 0.0 1.0 0.0 1.0 1.0 0.0
 0.0 0.0 1.0 0.0 0.0 0.0 1.0 1.0 0.0 0.0 0.0 1.0 1.0 1.0 0.0 0.0 1.0 0.0 1.0 0.0 0.0 1.0 0.0 1.0 1.0 0.0
 0.0 0.0 1.0 0.0 0.0 0.0 1.0 1.0 0.0 0.0 0.0 1.0 1.0 … 1.0 0.0 0.0 1.0 0.0 1.0 0.0 0.0 1.0 0.0 1.0 1.0 0.0
 0.0 1.0 1.0 0.0 0.0 0.0 1.0 1.0 0.0 0.0 0.0 1.0 1.0 1.0 0.0 0.0 1.0 0.0 1.0 0.0 0.0 1.0 0.0 1.0 0.0 0.0
 0.0 1.0 1.0 0.0 0.0 0.0 1.0 1.0 0.0 0.0 0.0 1.0 1.0 1.0 0.0 0.0 1.0 0.0 1.0 0.0 0.0 1.0 0.0 1.0 0.0 0.0
 0.0 1.0 1.0 0.0 0.0 0.0 1.0 1.0 0.0 0.0 0.0 1.0 1.0 1.0 0.0 0.0 1.0 0.0 1.0 0.0 0.0 1.0 0.0 1.0 0.0 0.0
 0.0 1.0 1.0 0.0 0.0 0.0 1.0 1.0 0.0 0.0 0.0 1.0 1.0 1.0 0.0 0.0 1.0 0.0 1.0 0.0 0.0 1.0 0.0 1.0 0.0 0.0
 0.0 1.0 1.0 0.0 0.0 0.0 1.0 1.0 0.0 0.0 0.0 1.0 1.0 … 1.0 0.0 0.0 1.0 0.0 1.0 0.0 0.0 1.0 0.0 1.0 0.0 0.0
 0.0 1.0 1.0 0.0 0.0 0.0 1.0 1.0 0.0 0.0 0.0 1.0 1.0 1.0 0.0 0.0 1.0 0.0 1.0 0.0 0.0 1.0 0.0 1.0 0.0 0.0
 0.0 1.0 1.0 0.0 0.0 0.0 1.0 1.0 0.0 0.0 0.0 1.0 1.0 1.0 0.0 0.0 1.0 0.0 1.0 0.0 0.0 1.0 0.0 1.0 0.0 0.0
 0.0 1.0 1.0 0.0 0.0 0.0 1.0 1.0 0.0 0.0 0.0 1.0 1.0 1.0 0.0 0.0 1.0 0.0 1.0 0.0 0.0 1.0 0.0 1.0 0.0 0.0
 0.0 1.0 1.0 0.0 0.0 0.0 1.0 1.0 0.0 0.0 0.0 1.0 1.0 1.0 0.0 0.0 1.0 0.0 1.0 0.0 0.0 1.0 0.0 1.0 0.0 0.0
 0.0 1.0 1.0 0.0 0.0 0.0 1.0 1.0 0.0 0.0 0.0 1.0 1.0 … 1.0 0.0 0.0 1.0 0.0 1.0 0.0 0.0 1.0 0.0 1.0 0.0 0.0

```

funnily enough, it looks like `cld` _does_ follow the rule:

```julia-auto
julia> maximum([(x-mod1(x, y))/y + 1 - cld(x,y) for x=-10000:.1:10000, y=[-100:.1:-.1; .1:.1:100]])
1.4551915228366852e-11

julia> [(x-mod1(x, y))/y + 1 - cld(x,y) for x=-1000:.1:1000, y=[-100:.1:-1.; 1:.1:100]]
20001×1982 Matrix{Float64}:
 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 … 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 … 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 … 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 … 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
 ⋮ ⋮ ⋮ ⋱ ⋮ ⋮ ⋮
 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
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 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 … 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
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 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 … 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
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 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 … 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 … 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

```

maybe it’s a bug, and `fld1` should actually just be a deprecated alias for `cld`?

logically speaking, I guess it would make sense for `divrem`, `fldmod`, `cldmod1` to all behave similarly

---

<div class="post-metadata">

**Author:** ![rokke](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/rokke/32/222691_2.png) [@rokke](https://discourse.julialang.org/u/rokke)\
**Post date:** [July 19, 2026, 1:07am UTC](https://discourse.julialang.org/t/why-is-fld1-not-named-cld1/138317/6 "2026-07-19T01:07:14Z")

</div>

the more I look at this the buggier it seems.

```julia-auto
julia> fld1(-0.533669923120631, 3.430469)
-1.0

julia> fld1(prevfloat(-0.533669923120631), 3.430469)
0.0

julia> fld1(nextfloat(-0.533669923120631), 3.430469)
0.0

```

submitted an [issue](https://github.com/JuliaLang/julia/issues/62426) to github