fix (#3847)

oscar-system · Jun 12, 2024 · 7e5d14d · 7e5d14d
1 parent 91f4c1d
commit 7e5d14d
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diff --git a/src/AlgebraicGeometry/Surfaces/K3Auto.jl b/src/AlgebraicGeometry/Surfaces/K3Auto.jl
@@ -2031,7 +2031,8 @@ function find_section(L::ZZLat, f::QQMatrix)
     k = nrows(K)
     Kl = integer_lattice(gram=K*transpose(K))
     # project ss to K
-    sK = solve(change_base_ring(QQ,K*transpose(K)),change_base_ring(QQ,K*transpose(ss)))
+    sK = solve(change_base_ring(QQ,K*transpose(K)),change_base_ring(QQ,K*transpose(ss)); side=:right
+    )
     a = QQ(1)
     cv = []
     while true

diff --git a/test/AlgebraicGeometry/Surfaces/K3Auto.jl b/test/AlgebraicGeometry/Surfaces/K3Auto.jl
@@ -154,3 +154,11 @@ end
   =#
 end
 
+@testset "find_section" begin
+  L = integer_lattice(gram=ZZ[0 2 3;  2 -2 1; 3 1 -2])
+  f = QQ[1 0 0;]
+  s = Oscar.find_section(L,f)
+  V = ambient_space(L)
+  @test inner_product(V,f,s)==1
+  @test inner_product(V,s,s)==-2
+end