From 7b7bea18f5b6dd09ef82ce7f1dc5734c308abf85 Mon Sep 17 00:00:00 2001
From: Paul Shen <pxshen@alumni.stanford.edu>
Date: Sat, 30 Dec 2023 15:40:56 -0500
Subject: [PATCH 1/2] Update README.md

---
 README.md | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/README.md b/README.md
index 02110e5..34bac49 100644
--- a/README.md
+++ b/README.md
@@ -1,5 +1,7 @@
 Working draft of a differentiable FDTD engine for inverse design in photonics, acoustics & RF.
-Documentation at https://github.io/paulxshen/differentiable-fdtd-beta-prerelease
+
+Documentation at https://github.io/differentiable-fdtd-beta-prerelease
+
 Discussion & updates at https://discourse.julialang.org/t/pre-ann-differentiable-fdtd-for-inverse-design-in-photonics-acoustics-and-rf/105405/12
 ![a](bend-pre.gif)
 ![b](bend-post.gif)

From 078fd9ddc1e423308cac1f2b74601ff901eae874 Mon Sep 17 00:00:00 2001
From: Paul Shen <pxshen@alumni.stanford.edu>
Date: Thu, 11 Jan 2024 14:59:08 -0500
Subject: [PATCH 2/2] h

---
 src/lazycat.jl | 46 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 46 insertions(+)
 create mode 100644 src/lazycat.jl

diff --git a/src/lazycat.jl b/src/lazycat.jl
new file mode 100644
index 0000000..b2439f5
--- /dev/null
+++ b/src/lazycat.jl
@@ -0,0 +1,46 @@
+struct Cat{T,N}<:AbstractArray{T,N}
+    v
+    dims
+ends
+sz
+len
+function Cat(a...;dims)
+ends=cumsum(size.(a,dims))
+sz=size(a[1])
+sz=(sz[1:dims-1],ends[end],sz[dims+1:end])
+len=sum(length.(a))
+    new{eltype(a[1]),ndims(a[1])}(a,dims,ends,sz,len)
+end
+end
+lcat(a...;dims)=Cat(a...;dims)
+lvcat(a...)=lcat(a...;dims=1)
+lhcat(a...)=lcat(a...;dims=2)
+Base.size(m::Cat)=m.sz
+Base.length(m::Cat)=m.len
+Base.collect(m::Cat)=cat(m.v...;dims=m.dims)
+Base.vec(m::Cat)=vcat(vec.(m.v)...;)
+function overlap(ends,i::Int)
+    vi=ss(ends,i)
+    if vi>1
+  return      [vi],[i-ends[vi-1]]
+    end
+     [vi],[i]
+        end
+function overlap(ends,r::)
+    (vi1,),(i1,)=overlap(ends,r[1])
+    (vi2,),(i2,)=overlap(ends,r[end])
+    vi1:vi2,[if vi==vi1
+    i1:ends[vi1]
+elseif vi==vi2
+    1:i2
+else
+    (:)
+end for vi=vi1:vi2]
+        end
+function Base.getindex(m::Cat,I...)
+@unpack v,dims,ends=m
+vi,vr=overlap(ends,I[dims])
+I1=I[1:dims-1]
+I2=I[dims+1:end]
+cat([v[i][I1...,r,I2...] for (i,r)=zip(vi,vr)]...;dims)
+end
\ No newline at end of file