From 4980c25029e393183b3d62c29d9f5bbb5b68c105 Mon Sep 17 00:00:00 2001
From: Benjamin K <benjamin.kulnik@student.tuwien.ac.at>
Date: Fri, 21 Feb 2025 11:08:38 +0100
Subject: [PATCH] add warnings for large arrays

add warnings for large arrays
---
 src/engine.jl  |  7 ++++++-
 src/mxarray.jl | 16 ++++++++++++++++
 2 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/src/engine.jl b/src/engine.jl
index f61f868..00ebcc8 100644
--- a/src/engine.jl
+++ b/src/engine.jl
@@ -180,8 +180,13 @@ function put_variable(session::MSession, name::Symbol, v::MxArray)
         string(name),
         v,
     )
+
+    # The size limit for `put_variable` is 2GB according to the MATLAB documentation, but seems to be a bit higher in practice.
+    # https://www.mathworks.com/help/matlab/apiref/engputvariable.html
     ret != 0 && throw(
-        MEngineError("failed to put variable $(name) into MATLAB session (err = $ret)"),
+        MEngineError(
+            "failed to put variable $(name) into MATLAB session (err = $ret). Ensure the that the variable name does not conflict with internal MATLAB names and that the size of the variable is below the MATLAB limit of 2GB.",
+        ),
     )
     return nothing
 end
diff --git a/src/mxarray.jl b/src/mxarray.jl
index ec1113c..c919b9c 100644
--- a/src/mxarray.jl
+++ b/src/mxarray.jl
@@ -256,6 +256,14 @@ mxarray(x::T) where {T<:MxComplexNum} = mxarray([x])
 # mxArray use Julia array's memory
 
 function mxarray(a::Array{T}) where {T<:MxRealNum}
+    # Check the array size
+    if sizeof(a) > 2 * 1024^3
+        @warn(
+            "Input array size exceeds the limit of 2 GB and is too large to be used with the MATLAB engine.",
+            maxlog = 1
+        )
+    end
+
     mx = mxarray(T, size(a))
     ccall(
         :memcpy,
@@ -269,6 +277,14 @@ function mxarray(a::Array{T}) where {T<:MxRealNum}
 end
 
 function mxarray(a::Array{T}) where {T<:MxComplexNum}
+    # Check the array size
+    if sizeof(a) > 2 * 1024^3
+        @warn(
+            "Input array size exceeds the limit of 2 GB and is too large to be used with the MATLAB engine.",
+            maxlog = 1
+        )
+    end
+
     mx = mxarray(T, size(a))
     na = length(a)
     rdat = unsafe_wrap(Array, real_ptr(mx), na)