Merge pull request #100 from ChrisRackauckas-Claude/fix-negative-info-nopivot

Fix negative info values for NoPivot() on Julia 1.11+

Author: ChrisRackauckas

.github/workflows/ci.yml

@@ -12,14 +12,14 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        julia-version: ['1']
+        julia-version: ['lts','1','pre']
         threads:
           - '1'
           - '3'
         os: [ubuntu-latest, windows-latest, macOS-latest]
     steps:
       - uses: actions/checkout@v4
-      - uses: julia-actions/setup-julia@v1
+      - uses: julia-actions/setup-julia@v2
         with:
           version: ${{ matrix.julia-version }}
       - uses: actions/cache@v4

src/lu.jl

@@ -21,6 +21,8 @@ function lu(A::AbstractMatrix, pivot = Val(true), thread = Val(false); kwargs...
 end
 
 const CUSTOMIZABLE_PIVOT = VERSION >= v"1.8.0-DEV.1507"
+# Julia 1.11+ uses negative info for NoPivot() failures
+const NOPIVOT_NEGATIVE_INFO = VERSION >= v"1.11.0-DEV"
 
 struct NotIPIV <: AbstractVector{BlasInt}
     len::Int
@@ -235,7 +237,14 @@ function reckernel!(A::AbstractMatrix{T}, pivot::Val{Pivot}, m, n, ipiv, info, b
         # A21 <- P2 A21
         Pivot && apply_permutation!(P2, A21, thread)
 
-        info != previnfo && (info += n1)
+        if info != previnfo
+            # Handle negative info for NoPivot (Julia 1.11+ convention)
+            if NOPIVOT_NEGATIVE_INFO && info < 0
+                info -= n1
+            else
+                info += n1
+            end
+        end
         if Pivot
             @turbo warn_check_args=false for i in 1:n2
                 P2[i] += n1
@@ -303,6 +312,10 @@ function _generic_lufact!(A, ::Val{Pivot}, ipiv, info) where {Pivot}
                 end
             elseif info == 0
                 info = k
+                # Julia 1.11+ convention: negative info for NoPivot
+                if !Pivot && NOPIVOT_NEGATIVE_INFO
+                    info = -info
+                end
             end
             k == minmn && break
             # Update the rest