index out of range when a function run at second time

Question

at

 result <- result + Convert.ToDouble(Gamma(input_miu_list.Length, 0))*(Miu_union(miu_list1, lambda) - Miu_union(miu_list2, lambda) - Miu_union(miu_list3, lambda) - Miu_union(miu_list4, lambda))

after jump to Miu_union second time, said index out of range

let Miu_union(a : List<double>, lambda : double) = 
    let mutable Miu_union_result : double = Convert.ToDouble(0)  // index out of range when debug break here at second time
    
    S(Miu(a.[0]), Miu(a.[1]), lambda)
    for i = 2 to a.Count-1 do
        Miu_union_result <- Miu_union_result + S(Miu_union_result, Miu(a.[i]), lambda)
    Miu_union_result
let hello... =
...
	result <- result + Convert.ToDouble(Gamma(input_miu_list.Length, 0))*(Miu_union(miu_list1, lambda) - Miu_union(miu_list2, lambda) - Miu_union(miu_list3, lambda) - Miu_union(miu_list4, lambda))

Answer 1

You are using index to get list elements. So probably when exception happens your list is empty or it's length is less than you are expecting.

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Petr