fix bug in extended_div() (#146)

Author: eeshan9815

src/intervals/arithmetic.jl

@@ -204,7 +204,8 @@ function extended_div(a::Interval{T}, b::Interval{T}) where T<:Real
             return (Interval(-Inf, a.lo / b.lo), Interval(a.lo / b.hi, Inf))
 
         end
-
+    elseif 0 ∈ a && 0 ∈ b
+        return (entireinterval(S), emptyinterval(S))
     else
         return (a / b, emptyinterval(S))
     end

test/interval_tests/numeric.jl

@@ -41,11 +41,13 @@ setprecision(Interval, Float64)
     @test extended_div(a, c) == (interval(2.4999999999999998e-02, 4.4e+00), emptyinterval(c))
     @test extended_div(c, interval(4.0)) == (interval(6.25e-02, 1e+00), emptyinterval(c))
     @test extended_div(c, zero(c)) == (emptyinterval(c), emptyinterval(c))
-    @test extended_div(interval( 0.0, 1.0), interval(0.0,1.0)) == (interval(0.0, Inf), emptyinterval(c))
+    @test extended_div(interval( 0.0, 1.0), interval(0.0,1.0)) == (entireinterval(c), emptyinterval(c))
     @test extended_div(interval(-1.0, 1.0), interval(0.0,1.0)) == (entireinterval(c), emptyinterval(c))
     @test extended_div(interval(-1.0, 1.0), interval(-1.0,1.0)) == (entireinterval(c), emptyinterval(c))
     @test extended_div(interval(1.0, 2.0), interval(-4.0, 4.0)) == ((-∞.. -0.25), (0.25..∞))
     @test extended_div(interval(-2.0, -1.0), interval(-2.0, 4.0)) == ((-∞.. -0.25), (0.5..∞))
+    @test extended_div(interval(0.0, 0.0), interval(-1.0, 1.0)) == (entireinterval(c), emptyinterval(c))
+
 
     a = @interval(1.e-20)
     @test a == Interval(1.0e-20, 1.0000000000000001e-20)