Fixed problem with non-compiling docs (reduce was hcat by default.

Author: benedict-96

src/build_function/build_function_double_input.jl

@@ -1,7 +1,7 @@
 """
     build_nn_function(eqs, nn, soutput)
 
-Build an executable function that can also depend on an output. It is then called with:
+Build an executable function that can also depend on an output. The resulting `built_function` is then called with:
 ```julia
 built_function(input, output, ps)
 ```
@@ -17,6 +17,7 @@ function build_nn_function(eqs, nn::AbstractSymbolicNeuralNetwork, soutput)
 end
 
 function build_nn_function(eq::EqT, sparams::NeuralNetworkParameters, sinput::Symbolics.Arr, soutput::Symbolics.Arr; reduce = hcat)
+    @assert ( (reduce == hcat) || (reduce == +) ) "Keyword reduce either has to be + or hcat!"
     gen_fun = _build_nn_function(eq, sparams, sinput, soutput)
     gen_fun_returned(input, output, ps) = mapreduce(k -> gen_fun(input, output, ps, k), reduce, axes(input, 2))
     function gen_fun_returned(x::AT, y::AT, ps) where {AT <: Union{AbstractVector, Symbolics.Arr}}

src/derivatives/pullback.jl

@@ -92,7 +92,7 @@ function SymbolicPullback(nn::SymbolicNeuralNetwork, loss::NetworkLoss)
     @variables soutput[1:output_dimension(nn.model)]
     symbolic_loss = loss(nn.model, params(nn), nn.input, soutput)
     symbolic_pullbacks = symbolic_pullback(symbolic_loss, nn)
-    pbs_executable = build_nn_function(symbolic_pullbacks, params(nn), nn.input, soutput)
+    pbs_executable = build_nn_function(symbolic_pullbacks, params(nn), nn.input, soutput; reduce = +)
     function pbs(input, output, params)
         pullback(::Union{Real, AbstractArray{<:Real}}) = _get_contents(_get_params(pbs_executable(input, output, params)))
         pullback
@@ -146,4 +146,4 @@ _get_contents(nt::Tuple{<:Union{NamedTuple, NeuralNetworkParameters}}) = nt[1]
 # (_pullback::SymbolicPullback)(ps, model, input_nt::QPTOAT)::Tuple = Zygote.pullback(ps -> _pullback.loss(model, ps, input_nt), ps)
 function (_pullback::SymbolicPullback)(ps, model, input_nt_output_nt::Tuple{<:QPTOAT, <:QPTOAT})::Tuple
     _pullback.loss(model, ps, input_nt_output_nt...), _pullback.fun(input_nt_output_nt..., ps)
-end
+end