From 9bdac76b2a6c74fa040b47d86c52703800271db3 Mon Sep 17 00:00:00 2001
From: lassepe <lasse.peters@mailbox.org>
Date: Fri, 6 Dec 2024 14:50:47 +0100
Subject: [PATCH] Fix edge-cases in symbolic backend handling

---
 src/game.jl | 5 +++--
 src/mcp.jl  | 8 +++++++-
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/src/game.jl b/src/game.jl
index 86a203d..cb8b934 100644
--- a/src/game.jl
+++ b/src/game.jl
@@ -74,7 +74,8 @@ function ParametricGame(;
     end
 
     # Build MCP representation.
-    F = Vector{Symbolics.Num}(
+    symbolic_type = eltype(x)
+    F = Vector{symbolic_type}(
         filter!(
             !isnothing,
             [
@@ -87,7 +88,7 @@ function ParametricGame(;
         ),
     )
 
-    z = Vector{Symbolics.Num}(
+    z = Vector{symbolic_type}(
         filter!(
             !isnothing,
             [
diff --git a/src/mcp.jl b/src/mcp.jl
index 34ae6b1..b89e091 100644
--- a/src/mcp.jl
+++ b/src/mcp.jl
@@ -60,10 +60,16 @@ function PrimalDualMCP(
     y_symbolic::Vector{T},
     θ_symbolic::Vector{T};
     compute_sensitivities = false,
-    backend = SymbolicUtils.SymbolicsBackend(),
     backend_options = (;),
 ) where {T<:Union{FD.Node,Symbolics.Num}}
     # Create symbolic slack variable `s` and parameter `ϵ`.
+    if T == FD.Node
+        backend = SymbolicUtils.FastDifferentiationBackend()
+    else
+        @assert T === Symbolics.Num
+        backend = SymbolicUtils.SymbolicsBackend()
+    end
+
     s_symbolic = SymbolicUtils.make_variables(backend, :s, length(y_symbolic))
     ϵ_symbolic = only(SymbolicUtils.make_variables(backend, :ϵ, 1))
     z_symbolic = [x_symbolic; y_symbolic; s_symbolic]