insucfficient precision in roots

thofma · Oct 13, 2023 · e4dcefe · e4dcefe
1 parent a8db55f
commit e4dcefe
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Showing 3 changed files with 11 additions and 2 deletions.
diff --git a/src/LocalField/Poly.jl b/src/LocalField/Poly.jl
@@ -835,7 +835,7 @@ function Hensel_factorization(f::Generic.Poly{T}) where T <: Union{padic, qadic,
   H = HenselCtxdr{T}(f, vlfp)
   lift(H, precision(f))
   for i = 1:H.n
-    D[ks[i]] = H.lf[i]
+    D[ks[i]] = setprecision(H.lf[i], precision(f))
   end
   return D
 end

diff --git a/src/LocalField/automorphisms.jl b/src/LocalField/automorphisms.jl
@@ -101,7 +101,7 @@ function _roots(f::Generic.Poly{T}) where T <: Union{padic, qadic, LocalFieldEle
   g = f(pi*x+r)
   g = divexact(g, _content(g))
   rtg = roots(g)
-  rts = elem_type(K)[setprecision(r, precision(y)) + pi*y for y in rtg]
+  rts = elem_type(K)[setprecision(r, precision(y)+1) + pi*y for y in rtg]
   return rts
 end
 

diff --git a/test/LocalField/Poly.jl b/test/LocalField/Poly.jl
@@ -79,6 +79,15 @@
     @test length(Hecke.slope_factorization(2*x+1)) == 1
   end
 
+  @testset "Roots" begin
+    _, t = PadicField(3, 10)["t"]
+    f = ((t-1+81)*(t-1+2*81))
+    rt = roots(f)
+    @test length(rt) == 2
+    @test rt[1] != rt[2]
+    @test all(iszero, map(f, rt))
+  end
+
   @testset "Resultant" begin
     R, x = polynomial_ring(PadicField(853, 2), "x")
     a = 4*x^5 + x^4 + 256*x^3 + 192*x^2 + 48*x + 4