#3495 - Avoid repeated creation of zero_box/sym_box

src/Initialization/init_IntervalArithmetic.jl

@@ -11,11 +11,55 @@ function vertices_list(H::IA.IntervalBox)
     return vertices_list(convert(Hyperrectangle, H))
 end
 
-const zero_itv(N) = IA.interval(zero(N))
-const sym_itv(N) = IA.interval(-one(N), one(N))
+const zero_itv_store = Dict{Type,IA.Interval}()
+function zero_itv(N)
+    res = get(zero_itv_store, N, nothing)
+    if isnothing(res)
+        res = IA.interval(zero(N))
+        zero_itv_store[N] = res
+    end
+    return res
+end
+
+const zero_box_store = Dict{Type,Dict{Integer,IA.IntervalBox}}()
+function zero_box(n::Int, N=Float64)
+    d = get(zero_box_store, N, nothing)
+    if isnothing(d)
+        d = Dict{Integer,IA.IntervalBox}()
+        zero_box_store[N] = d
+    end
+    res = get(d, n, nothing)
+    if isnothing(res)
+        res = IA.IntervalBox(zero_itv(N), n)
+        d[n] = res
+    end
+    return res
+end
 
-zero_box(n::Int, N=Float64) = IA.IntervalBox(zero_itv(N), n)
-sym_box(n::Int, N=Float64) = IA.IntervalBox(sym_itv(N), n)
+const sym_itv_store = Dict{Type,IA.Interval}()
+function sym_itv(N)
+    res = get(sym_itv_store, N, nothing)
+    if isnothing(res)
+        res = IA.interval(-one(N), one(N))
+        sym_itv_store[N] = res
+    end
+    return res
+end
+
+const sym_box_store = Dict{Type,Dict{Integer,IA.IntervalBox}}()
+function sym_box(n::Int, N=Float64)
+    d = get(sym_box_store, N, nothing)
+    if isnothing(d)
+        d = Dict{Integer,IA.IntervalBox}()
+        sym_box_store[N] = d
+    end
+    res = get(d, n, nothing)
+    if isnothing(res)
+        res = IA.IntervalBox(sym_itv(N), n)
+        d[n] = res
+    end
+    return res
+end
 
 """
     fast_interval_pow(a::IntervalArithmetic.Interval, n::Int)