Support type promotion in ShiftedOperator

Updated ShiftedOperator to promote types between operator and shift value, ensuring consistent output types. Added tests to verify type promotion and correct behavior when mixing Float32 and Float64 inputs. Also added a reset! function to ShiftedOperator for resetting operation counters.

Author: farhadrclass

src/shifted_operators.jl

@@ -94,9 +94,11 @@ function ShiftedOperator(
   )
 end
 
-function ShiftedOperator(H::OpH, σ::T = zero(eltype(H))) where {T, OpH}
+function ShiftedOperator(H::OpH, σ_in::Number = zero(eltype(H))) where {OpH}
+  T = promote_type(eltype(H), typeof(σ_in))
 
-  data = ShiftedData(H, σ)
+  data = ShiftedData(H, σ_in)
+  σ = convert(T, σ_in)
 
   prod! = (y, x, α, β) -> shifted_prod!(y, data, x, α, β)
   tprod! = (y, x, α, β) -> shifted_tprod!(y, data, x, α, β)
@@ -130,3 +132,10 @@ function adjoint(op::ShiftedOperator)
   # (H + σI)ᴴ = Hᴴ + conj(σ)I
   return ShiftedOperator(adjoint(op.data.H), conj(op.data.σ))
 end
+
+function reset!(op::ShiftedOperator)
+  op.nprod = 0
+  op.ntprod = 0
+  op.nctprod = 0
+  return op
+end

test/test_shifted_operator.jl

@@ -85,4 +85,22 @@
     @test !(y1 ≈ y2)
     @test y2 ≈ (H_dense + 10.0*I) * x
   end
+  @testset "Type Promotion" begin
+    # H is Float32
+    H = LinearOperator(rand(Float32, 5, 5))
+
+    # σ is Float64
+    σ = 1.0 # default Float64
+
+    op = ShiftedOperator(H, σ)
+
+    # The operator itself should be Float64 (promoted)
+    @test eltype(op) == Float64
+    @test op.data.σ isa Float64
+
+    # Ensure operations return the promoted type
+    x = rand(Float32, 5)
+    y = op * x
+    @test eltype(y) == Float64
+  end
 end