few more iszero() fix

Author: lrnv

test/chainrules.jl

@@ -209,7 +209,7 @@
             # Forward db
             _, Δx_inv_db = frule((NoTangent(), 0.0, 1.0, 0.0), beta_inc_inv, a, b, p)
             _, Δp_from_db = frule((NoTangent(), 0.0, 1.0, Δx_inv_db[1]), beta_inc, a, b, x_inv)
-            @test isapprox(Δp_from_db[1], 0.0; rtol=1e-9)
+            @test iszero(Δp_from_db[1])
 
             # Reverse-mode chain for composition: pullback through f then g
             # Pullback of f at (a,b,x_inv)
@@ -221,9 +221,9 @@
             ā_total = āf + āg
             b̄_total = b̄f + b̄g
             p̄_total = p̄g
-            @test isapprox(ā_total, 0.0; rtol=1e-10)
-            @test isapprox(b̄_total, 0.0; rtol=1e-10)
-            @test isapprox(p̄_total, 1.0; rtol=1e-9)
+            @test iszero(ā_total)
+            @test iszero(b̄_total)
+            @test iszero(p̄_total)
         end
 
         @testset "incomplete beta: basic test_frule/test_rrule" begin