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cumul_integrate gives wrong result? #43

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islent opened this issue Mar 4, 2022 · 1 comment
Open

cumul_integrate gives wrong result? #43

islent opened this issue Mar 4, 2022 · 1 comment

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@islent
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islent commented Mar 4, 2022

julia> x = collect(1.0:5.0)
5-element Vector{Float64}:
 1.0
 2.0
 3.0
 4.0
 5.0

julia> y = x.^2
5-element Vector{Float64}:
  1.0
  4.0
  9.0
 16.0
 25.0

julia> cumul_integrate(x, y)
5-element Vector{Float64}:
  2.5
  5.0
 11.5
 24.0
 44.5

The result is different from
https://www.mathworks.com/help/matlab/ref/cumtrapz.html

Should we expect an array like [2.5, 9.0, 21.5, 42.0] from cumul_integrate?

@natgeo-wong
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This is late, but I know what you have to do to get the cumtrapz result, which is the correct result.

You need to do z = cumul_integrate(x, y) and then do z = z[2:end] .- z[1]

I'll see if the original owner is still active.

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