Inplace Operation

SciML · Feb 6, 2021 · 61366b5 · 61366b5
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commit 61366b5
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Showing 3 changed files with 18 additions and 20 deletions.
diff --git a/examples/Fast_Diffusion.jl b/examples/Fast_Diffusion.jl
@@ -26,15 +26,15 @@ m = 1                                   # Inner differential order
 approx_ord = 2                               
 
 u0 = u_analytic.(knots,0.0)
-
+du = similar(u0)
 t0 = 0.0
 t1 = 1.0
 
-function f(u,p,t)
+function f(du,u,p,t)
     bc = DirichletBC(exp(-t),(1.0 + exp(2*t))^(-0.5))
     l = bc*u
     k = l.^(-2)                        # Diffusion Coefficient
-    NonLinearDiffusion(n,m,approx_ord,k,l,h,nknots)
+    NonLinearDiffusion!(du,n,m,approx_ord,k,l,h,nknots)
 end
 
 prob = ODEProblem(f, u0, (t0, t1))

diff --git a/src/DiffEqOperators.jl b/src/DiffEqOperators.jl
@@ -59,7 +59,7 @@ end
 export MatrixFreeOperator
 export AnalyticalJacVecOperator, JacVecOperator, getops
 export AbstractDerivativeOperator, DerivativeOperator,
-       CenteredDifference, UpwindDifference, NonLinearDiffusion
+       CenteredDifference, UpwindDifference, NonLinearDiffusion!
 export DirichletBC, Dirichlet0BC, NeumannBC, Neumann0BC, RobinBC, GeneralBC, MultiDimBC, PeriodicBC,
        MultiDimDirectionalBC, ComposedMultiDimBC
 export compose, decompose, perpsize

diff --git a/src/derivative_operators/derivative_operator.jl b/src/derivative_operators/derivative_operator.jl
@@ -26,29 +26,27 @@ struct DerivativeOperator{T<:Real,N,Wind,T2,S1,S2<:SArray,T3,F} <: AbstractDeriv
     coeff_func              :: F
 end
 
-struct NonLinearDiffusion end
+struct NonLinearDiffusion! end
+
+function NonLinearDiffusion!(du::AbstractVector{T}, second_differential_order::Int, first_differential_order::Int, approx_order::Int,
+    p::AbstractVector{T}, q::AbstractVector{T}, dx::Union{T , AbstractVector{T} , Real},
+    nknots::Int) where {T<:Real, N}
+    #q is given by bc*u , u being the unknown function
+    #p is given as some function of q , p being the diffusion coefficient
 
-function NonLinearDiffusion(second_differential_order::Int, first_differential_order::Int, approx_order::Int,
-                            p::AbstractVector{T}, q::AbstractVector{T}, dx::Union{T , AbstractVector{T} , Real},
-                            nknots::Int) where {T<:Real,N}
-    #p is given by bc1*k , k being the diffusion coefficient
-    #q is given by bc2*u , u being the desired function
     @assert approx_order>1 "approximation_order must be greater than 1."
-    discretization = zeros(nknots);
-
     if first_differential_order > 0 
-        discretization += (CenteredDifference(first_differential_order,approx_order,dx,nknots)*q).*(CenteredDifference(second_differential_order,approx_order,dx,nknots)*p);
+    du .= (CenteredDifference(first_differential_order,approx_order,dx,nknots)*q).*(CenteredDifference(second_differential_order,approx_order,dx,nknots)*p)
     else 
-        discretization += q[2:(nknots + 1)].*(CenteredDifference(second_differential_order,approx_order,dx,nknots)*p); 
+    du .= q[2:(nknots + 1)].*(CenteredDifference(second_differential_order,approx_order,dx,nknots)*p)
     end
-    
+
     for l = 1:(second_differential_order - 1)
-        discretization += binomial(second_differential_order,l)*(CenteredDifference(l + first_differential_order,approx_order,dx,nknots)*q).*(CenteredDifference(second_differential_order - l,approx_order,dx,nknots)*p);
+    du .= du .+ binomial(second_differential_order,l)*(CenteredDifference(l + first_differential_order,approx_order,dx,nknots)*q).*(CenteredDifference(second_differential_order - l,approx_order,dx,nknots)*p)
     end
-
-    discretization += (CenteredDifference(first_differential_order + second_differential_order,approx_order,dx,nknots)*q).*p[2:(nknots + 1)];
-    return discretization
-
+
+    du .= du .+ (CenteredDifference(first_differential_order + second_differential_order,approx_order,dx,nknots)*q).*p[2:(nknots + 1)]
+
 end
 
 struct CenteredDifference{N} end