Merge commit '8f326d14599d3030c626c46532d8e8534c1cdbec' into HEAD

Author: yashikno

.gitattributes

@@ -4,3 +4,4 @@
 *.py text diff=python
 *.tex text diff=tex
 lib/** binary
+lib/eigen_5.0.1/STAN_CHANGES.md -binary text diff=markdown

.github/workflows/header_checks.yml

@@ -26,8 +26,8 @@ jobs:
     runs-on: windows-latest
 
     steps:
-    - uses: actions/checkout@v6
-    - uses: actions/setup-python@v6
+    - uses: actions/checkout@v7
+    - uses: actions/setup-python@v7
       with:
         python-version: '3.x'
 
@@ -52,7 +52,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v6
+    - uses: actions/checkout@v7
 
     - name: Run header tests
       run: |
@@ -63,7 +63,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v6
+    - uses: actions/checkout@v7
 
     - name: Run header tests
       run: |

.github/workflows/main.yml

@@ -25,6 +25,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       fail-fast: false
+      max-parallel: 5
       matrix:
         os: [windows-11-arm, windows-latest, ubuntu-24.04-arm]
         config: [
@@ -36,31 +37,21 @@ jobs:
         ]
 
     steps:
-    - uses: actions/checkout@v6
-    - uses: actions/setup-python@v6
+    - uses: actions/checkout@v7
+    - uses: actions/setup-python@v7
       with:
         python-version: '3.x'
 
     - name: Download and Install Rtools45
       if: runner.os == 'Windows'
-      run: |
-        $ARCH = if ('${{ matrix.os }}' -eq 'windows-11-arm') { 'aarch64' } else { 'x86_64' }
-        $RTOOLS = if ('${{ matrix.os }}' -eq 'windows-11-arm') { "rtools45-$ARCH" } else { 'rtools45' }
-
-        # Installation will hang if the toolchain is already installed
-        if (-Not $(Test-Path -Path "C:/$RTOOLS")) {
-          Invoke-WebRequest `
-              -Uri https://github.com/r-hub/rtools45/releases/download/latest/$RTOOLS.exe `
-              -OutFile "$RTOOLS.exe"
-          Start-Process -FilePath "$RTOOLS.exe" -ArgumentList "/INSTALL /VERYSILENT /SUPPRESSMSGBOXES" -Wait
-        }
-
-        echo "C:/$RTOOLS/usr/bin;C:/$RTOOLS/$ARCH-w64-mingw32.static.posix/bin" | Out-File -Append -FilePath $env:GITHUB_PATH -Encoding utf8
-        echo "$(pwd)/lib/tbb" | Out-File -Append -FilePath $env:GITHUB_PATH -Encoding utf8
+      uses: r-lib/actions/setup-r@v2
+      with:
+        r-version: 'release'
 
     - name: Build Math libs
       shell: pwsh
       run: |
+        echo "$(pwd)/lib/tbb" | Out-File -Append -FilePath $env:GITHUB_PATH -Encoding utf8
         Add-Content make\local "CPPFLAGS=-w -Wno-psabi -Wno-misleading-indentation`n"
         Add-Content make\local "STAN_THREADS=true`n"
         make -f make/standalone math-libs -j2
@@ -82,36 +73,28 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       fail-fast: false
+      max-parallel: 5
       matrix:
         os: [windows-11-arm, windows-latest, ubuntu-24.04-arm]
         group: [1, 2, 3, 4, 5]
 
     steps:
-    - uses: actions/checkout@v6
-    - uses: actions/setup-python@v6
+    - uses: actions/checkout@v7
+    - uses: actions/setup-python@v7
       with:
         python-version: '3.x'
 
     - name: Download and Install Rtools45
       if: runner.os == 'Windows'
-      run: |
-        $ARCH = if ('${{ matrix.os }}' -eq 'windows-11-arm') { 'aarch64' } else { 'x86_64' }
-        $RTOOLS = if ('${{ matrix.os }}' -eq 'windows-11-arm') { "rtools45-$ARCH" } else { 'rtools45' }
-
-        # Installation will hang if the toolchain is already installed
-        if (-Not $(Test-Path -Path "C:/$RTOOLS")) {
-          Invoke-WebRequest `
-              -Uri https://github.com/r-hub/rtools45/releases/download/latest/$RTOOLS.exe `
-              -OutFile "$RTOOLS.exe"
-          Start-Process -FilePath "$RTOOLS.exe" -ArgumentList "/INSTALL /VERYSILENT /SUPPRESSMSGBOXES" -Wait
-        }
-
-        echo "C:/$RTOOLS/usr/bin;C:/$RTOOLS/$ARCH-w64-mingw32.static.posix/bin" | Out-File -Append -FilePath $env:GITHUB_PATH -Encoding utf8
-        echo "$(pwd)/lib/tbb" | Out-File -Append -FilePath $env:GITHUB_PATH -Encoding utf8
+      uses: r-lib/actions/setup-r@v2
+      with:
+        r-version: 'release'
+
 
     - name: Build Math libs
       shell: pwsh
       run: |
+        echo "$(pwd)/lib/tbb" | Out-File -Append -FilePath $env:GITHUB_PATH -Encoding utf8
         Add-Content make\local "CPPFLAGS=-w -Wno-psabi -Wno-misleading-indentation`n"
         Add-Content make\local "STAN_THREADS=true`n"
         make -f make/standalone math-libs -j2

RELEASE-NOTES.txt

@@ -1,5 +1,23 @@
 Stan Math Library Release Notes
 
+======================================================================
+v5.3.0 (19 May 2026)
+======================================================================
+
+ - Improved the embedded Laplace approximation. (#3250, #3286, #3297, #3281)
+ - Added `yule_simon_lcdf`, `yule_simon_cdf`, and `yule_simon_rng`. (#3276, #3283, #3285)
+ - Added quantile function for student-t distribution. (#3211)
+ - Added `trace_dot(A, B)`. (#3310)
+ - Improved the robustness of `gamma_lccdf`. (#3275, #3272, #3292, #3296)
+ - Set thread QoS to USER_INITIATED on Apple Silicon. (#3278)
+ - Updated tests to ensure they properly clean up memory. (#3293)
+ - Fixed typos in error messages, code comments. (#3295)
+ - Documented parameter 'y' in apply_scalar_binary. (#3284)
+ - Jenkins: change how gh-pages branch gets re-built. (#3316)
+ - Jenkins: improved error handling of parallel distribution tests. (#3307)
+ - Updated OpenCL C++ to use v2025.07.22. (#3298)
+ - Updated cpplint to 2.0.2. (#3294)
+
 ======================================================================
 v5.2.0 (13 January 2026)
 ======================================================================

doxygen/contributor_help_pages/getting_started.md

@@ -660,9 +660,15 @@ The values of `x` have the same shape as `x`.
 
 ### Values and adjoint extensions to Eigen
 
-The matrix and vector autodiff types come with an extra `.val()` and `.adj()`, member functions called `.val_op()` and `.adj_op()`.
-These `*_op()` member functions are used as a workaround for a bug in Eigen where transpose expressions will be inaccessible because of an incorrect const reference.
-See [here](https://github.com/stan-dev/math/issues/2653) for the details and other information for when this workaround is needed.
+By default, `.val()` and `.adj()` return a `CwiseUnaryView` when the matrix/vector is non-`const`,
+and returns a `CwiseUnaryOp` when the matrix/vector is `const`. The exception is that
+calling `.val()` on a matrix/vector of `var` types will always return a `CwiseUnaryOp`, as the
+underlying value is always `const`.
+
+However, using a `CwiseUnaryView` in some Eigen operations (e.g., multiplication, transposition)
+can result in a compilation error. To workaround this, the `.val_op()` and `.adj_op()` member
+functions have been added to explicitly request a `CwiseUnaryOp` regardless of whether the
+matrix/vector is `const` or not.
 
 The member functions `.val()` and `.val_op()` return expressions that evaluate to the values
 of the autodiff matrix.

doxygen/doxygen.cfg

@@ -2292,7 +2292,7 @@ SEARCH_INCLUDES        = YES
 
 INCLUDE_PATH           = ./ \
                          lib/tbb_2020.3/include \
-                         lib/eigen_3.4.0 \
+                         lib/eigen_5.0.1 \
                          lib/sundials_6.1.1/include \
                          lib/sundials_6.1.1/src/sundials \
                          lib/opencl_v2025.07.22 \