Cannot get correct bin number

[Y.S.Zhang]

Dear experts,
I am wondering why the following gives incorrect bin number.

root [0]   float d[4] = {1.8, 2, 3 ,4}

root [1] TH1D h4("h4", "", 3, d)

root [2] h4.FindBin(1.8)

(int) 1

root [4]  float e[4] = {1.7, 2, 3 ,4}

root [5] TH1D h3("h3", "", 3, e)

root [6] h3.FindBin(1.7)

(int) 0

Seems it is a bug

---

ROOT Version: TH1D h4(“h4”, “”, 3, d)
Platform: Ubuntu 18
Compiler: gcc (Ubuntu 7.3.0-27ubuntu1~18.04) 7.3.0

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[Wile_E_Coyote]

Try with:

double d[4] = ...
double e[4] = ...

P.S. Google for “floating point rounding error”, “round-off error”, “floating point arithmetic precision”, and so on.

[Y.S.Zhang]

Thank you, it works.