How can I make sure that by adding 0.2 at every iteration I get the correct result?
some = 0.0
for i in 1:10
some += 0.2
println(some)
end
the code above gives me
0.2
0.4
0.6000000000000001
0.8
1.0
1.2
1.4
1.5999999999999999
1.7999999999999998
1.9999999999999998
Floats are only approximatively correct and if adding up to infinity the error will become infinite, but you can still calculate with it pretty precisely. If you need to evaluate the result and look if it is correct you can use isapprox(a,b) or a ≈ b.
I.e.
some = 0.
for i in 1:1000000
some += 0.2
end
isapprox(some, 1000000 * 0.2)
# true
Otherwise, you can add integer numbers in the for loop and then divide by 10.
some = 0.
for i in 1:10
some += 2.
println(some/10.)
end
#0.2
#0.4
#0.6
#0.8
#1.0
#1.2
#1.4
#1.6
#1.8
#2.0
More info about counting with floats: https://en.wikipedia.org/wiki/Floating-point_arithmetic
You can iterate over a range since they use some clever tricks to return more "natural" values:
julia> collect(0:0.2:2)
11-element Vector{Float64}:
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
julia> collect(range(0.0, step=0.2, length=11))
11-element Vector{Float64}:
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0