coprime BB fixed

all tests pass

Author: esabo

src/Quantum/product_codes.jl

@@ -984,16 +984,15 @@ function CoprimeBivariateBicycleCode(a::ResElem, b::ResElem)
 
     P = x * y
     A = zero_matrix(F, deg_P, deg_P)
-    for ex in exponents(lift(a))
-        # println(ex)
-        power, _ = findmax(ex)
-        A += P^power
+    exps = findall(i -> !is_zero(i), collect(coefficients(lift(a)))) .- 1
+    for ex in exps
+        A += P^ex
     end
 
     B = zero_matrix(F, deg_P, deg_P)
-    for ex in exponents(lift(b))
-        power, _ = findmax(ex)
-        B += P^power
+    exps = findall(i -> !is_zero(i), collect(coefficients(lift(b)))) .- 1
+    for ex in exps
+        B += P^ex
     end
 
     return CSSCode(hcat(A, B), hcat(transpose(B), transpose(A)))

test/Quantum/product_codes_test.jl

@@ -606,64 +606,64 @@
         @test_broken minimum_distance(S) == 8
     end
 
-    # @testset "CoprimeBivariateBicycleCode" begin
-    #     # coprime bivariate bicycle codes
-    #     S, P = polynomial_ring(Oscar.Nemo.Native.GF(2), :P)
-
-    #     # Table 2 of https://arxiv.org/pdf/2408.10001v1
-    #     # [[30, 4, 6]]
-    #     l = 3
-    #     m = 5
-    #     R, _ = residue_ring(S, P^(l * m) - 1)
-    #     a = R(1 + P + P^2)
-    #     b = R(P + P^3 + P^8)
-    #     Q = CoprimeBivariateBicycleCode(a, b)
-    #     @test length(Q) == 30
-    #     @test dimension(Q) == 4
-    #     @test_broken minimum_distance(Q) == 6
-
-    #     # [[42, 6, 6]]
-    #     l = 3
-    #     m = 7
-    #     R, _ = residue_ring(S, P^(l * m) - 1)
-    #     a = R(1 + P^2 + P^3)
-    #     b = R(P + P^3 + P^11)
-    #     Q = CoprimeBivariateBicycleCode(a, b)
-    #     @test length(Q) == 42
-    #     @test dimension(Q) == 6
-    #     @test_broken minimum_distance(Q) == 6
-
-    #     # [[70, 6, 8]]
-    #     l = 5
-    #     m = 7
-    #     R, _ = residue_ring(S, P^(l * m) - 1)
-    #     a = R(1 + P + P^5)
-    #     b = R(1 + P + P^12)
-    #     Q = CoprimeBivariateBicycleCode(a, b)
-    #     @test length(Q) == 70
-    #     @test dimension(Q) == 6
-    #     @test_broken minimum_distance(Q) == 8
-
-    #     # [[108, 12, 6]]
-    #     l = 2
-    #     m = 27
-    #     R, _ = residue_ring(S, P^(l * m) - 1)
-    #     a = R(P^2 + P^5 + P^44)
-    #     b = R(P^8 + P^14 + P^47)
-    #     Q = CoprimeBivariateBicycleCode(a, b)
-    #     @test length(Q) == 108
-    #     @test dimension(Q) == 12
-    #     @test_broken minimum_distance(Q) == 6
-
-    #     # [[126, 12, 10]]
-    #     l = 7
-    #     m = 9
-    #     R, _ = residue_ring(S, P^(l * m) - 1)
-    #     a = R(1 + P + P^58)
-    #     b = R(P^3 + P^16 + P^44)
-    #     Q = CoprimeBivariateBicycleCode(a, b)
-    #     @test length(Q) == 126
-    #     @test dimension(Q) == 12
-    #     @test_broken minimum_distance(Q) == 10
-    # end
+    @testset "CoprimeBivariateBicycleCode" begin
+        # coprime bivariate bicycle codes
+        S, P = polynomial_ring(Oscar.Nemo.Native.GF(2), :P)
+
+        # Table 2 of https://arxiv.org/pdf/2408.10001v1
+        # [[30, 4, 6]]
+        l = 3
+        m = 5
+        R, _ = residue_ring(S, P^(l * m) - 1)
+        a = R(1 + P + P^2)
+        b = R(P + P^3 + P^8)
+        Q = CoprimeBivariateBicycleCode(a, b)
+        @test length(Q) == 30
+        @test dimension(Q) == 4
+        @test_broken minimum_distance(Q) == 6
+
+        # [[42, 6, 6]]
+        l = 3
+        m = 7
+        R, _ = residue_ring(S, P^(l * m) - 1)
+        a = R(1 + P^2 + P^3)
+        b = R(P + P^3 + P^11)
+        Q = CoprimeBivariateBicycleCode(a, b)
+        @test length(Q) == 42
+        @test dimension(Q) == 6
+        @test_broken minimum_distance(Q) == 6
+
+        # [[70, 6, 8]]
+        l = 5
+        m = 7
+        R, _ = residue_ring(S, P^(l * m) - 1)
+        a = R(1 + P + P^5)
+        b = R(1 + P + P^12)
+        Q = CoprimeBivariateBicycleCode(a, b)
+        @test length(Q) == 70
+        @test dimension(Q) == 6
+        @test_broken minimum_distance(Q) == 8
+
+        # [[108, 12, 6]]
+        l = 2
+        m = 27
+        R, _ = residue_ring(S, P^(l * m) - 1)
+        a = R(P^2 + P^5 + P^44)
+        b = R(P^8 + P^14 + P^47)
+        Q = CoprimeBivariateBicycleCode(a, b)
+        @test length(Q) == 108
+        @test dimension(Q) == 12
+        @test_broken minimum_distance(Q) == 6
+
+        # [[126, 12, 10]]
+        l = 7
+        m = 9
+        R, _ = residue_ring(S, P^(l * m) - 1)
+        a = R(1 + P + P^58)
+        b = R(P^3 + P^16 + P^44)
+        Q = CoprimeBivariateBicycleCode(a, b)
+        @test length(Q) == 126
+        @test dimension(Q) == 12
+        @test_broken minimum_distance(Q) == 10
+    end
 end