Simplify Julia implementation

Co-authored-by: Michael Abbott <[email protected]>

Author: giordano

src/leibniz.jl

@@ -1,22 +1,2 @@
-struct SignVector <: AbstractVector{Float64}
-    len::Int
-end
-Base.size(s::SignVector) = (s.len,)
-Base.getindex(::SignVector, i::Int) = Float64((-1)^iseven(i))
-
-function f(rounds)
-    xs = SignVector(rounds + 2)
-    pi = 1.0
-
-    @simd for i in 2:(rounds + 2)
-        x = xs[i]
-        pi += x / (2 * i - 1)
-    end
-
-    return pi*4
-end
-
-@static if abspath(PROGRAM_FILE) == @__FILE__
-    rounds = parse(Int64, readchomp("rounds.txt"))
-    print(f(rounds))
-end
+f(n) = sum(i -> 4/(4i-2n-3), 1:n)
+abspath(PROGRAM_FILE) == @__FILE__ && print(f(parse(Int, readchomp("rounds.txt"))))