small typos in julia code that could be a problem in other languages. Added abs and fixed <= (#840)

* small typo in julia code that could be a problem in other languages

* adding absolute value to approximate counting tests in Julia

Author: leios

contents/approximate_counting/code/julia/approximate_counting.jl

@@ -17,7 +17,7 @@ function increment(v, a)
     delta = 1/(n(v+1, a)-n(v, a))
 
     if rand() <= delta
-        return v += 1
+        return v + 1
     else
         return v
     end
@@ -47,7 +47,7 @@ function test_approximate_count(n_trials, n_items, a, threshold)
 
     avg = sum(samples)/n_trials
 
-    @test ((avg - n_items) / n_items < threshold)
+    @test (abs((avg - n_items) / n_items) < threshold)
 end
 
 @testset "Counting Tests, 100 trials" begin