# After scaling the vector still not summing up to 1

**URL:** <https://discourse.julialang.org/t/after-scaling-the-vector-still-not-summing-up-to-1/35460>\
**Category:** General Usage\
**Created:** [March 3, 2020, 12:09pm UTC](https://discourse.julialang.org/t/after-scaling-the-vector-still-not-summing-up-to-1/35460 "2020-03-03T12:09:56Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![1634](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/1634/32/12119_2.png) [@1634](https://discourse.julialang.org/u/1634)\
**Post date:** [March 3, 2020, 12:09pm UTC](https://discourse.julialang.org/t/after-scaling-the-vector-still-not-summing-up-to-1/35460/1 "2020-03-03T12:09:56Z")

</div>

```julia
a=[0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.000999000999000999, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.01098901098901099, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 
    0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.000999000999000999, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 
    0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.04595404595404595, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.01098901098901099, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.4005994005994006, 0.0979020979020979, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0979020979020979, 0.0, 0.0, 0.0, 0.23776223776223776, 0.0959040959040959]
#at most 17-digit

#before scale
sum(a) #0.9999999999999999 #16-digit

a=round.(a,digits=15) #or digits=10 all tried
a2=a/sum(a) #try to make a sum up to 1

#after scale at end
sum(a2) # printed as 1.0000000000000002 #16-digit

```

The rounding before scaling seems to work for this MWE but in my original for loop codes it still return 1.0000000000000002 as the sum of the column vector.

---

<div class="post-metadata">

**Author:** ![fredrikekre](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/fredrikekre/32/1688_2.png) [@fredrikekre](https://discourse.julialang.org/u/fredrikekre)\
**Post date:** [March 3, 2020, 12:14pm UTC](https://discourse.julialang.org/t/after-scaling-the-vector-still-not-summing-up-to-1/35460/2 "2020-03-03T12:14:00Z")

</div>

See [PSA: floating-point arithmetic](https://discourse.julialang.org/t/psa-floating-point-arithmetic/8678).