Update version, CHANGELOG, and examples

Author: ikorotkin

docs/CHANGELOG.md

@@ -8,11 +8,25 @@ nav_order: 11
 
 All notable user-facing changes to the `dae-cpp` project are documented in this page.
 
-## v2.0.1
+## v2.1.0
 
 New
 {: .label .label-green }
 
+Version 2.1 allows the user to define the shape (structure) of the Jacobian matrix. I.e., instead of providing analytic Jacobian (or not providing it at all, which is slow if the system is large enough), the user can specify the positions of non-zero elements in the Jacobian. The solver will use automatic differentiation for the specified elements only. This works nearly as fast as analytic Jacobian without requiring the user to differentiate the vector function manually.
+
+- Added `JacobianMatrixShape` and `VectorFunctionElements` helper classes to define the Jacobian matrix shape and the vector function
+- Added `JacobianCompare` class that helps the user to compare the user-defined Jacobian (either defined explicitly or using Jacobian shape) with the one computed automatically from the system RHS
+- Added `jacobian_shape` and `jacobian_compare` examples
+- Updated `autodiff` to `v1.1.2`
+- Updated Eigen (commit from 28th March 2024, see issue [#52](https://github.com/dae-cpp/dae-cpp/issues/52))
+- Updated `googletest` from `v.1.14.x` to `v1.15.2`
+- Added integration test that uses Jacobian derived from the given shape
+- Added unit tests for all new classes (`JacobianMatrixShape`, `VectorFunctionElements`, `JacobianCompare`)
+- Minor solver updates
+
+## v2.0.1
+
 - Added [Flame Propagation](https://github.com/dae-cpp/dae-cpp/blob/master/examples/flame_propagation/flame_propagation.cpp) example (stiff equation)
 - Added `daecpp::dual_type` for automatic differentiation of the vector function (used in [Flame Propagation](https://github.com/dae-cpp/dae-cpp/blob/master/examples/flame_propagation/flame_propagation.cpp) example)
 - Added integration test based on the "Flame Propagation" example

docs/examples.md

@@ -42,3 +42,21 @@ When you light a match, the ball of flame grows rapidly until it reaches a criti
 Then it remains at that size because the amount of oxygen being consumed by the combustion
 in the interior of the ball balances the amount of oxigen available through the surface.
 This example solves **stiff** equation of flame propagation for the scalar variable $$y(t)$$ which represents the radius of the ball.
+
+## Jacobian matrix shape
+
+Jacobian matrix shape source file example: [jacobian_shape.cpp](https://github.com/dae-cpp/dae-cpp/blob/master/examples/jacobian_shape/jacobian_shape.cpp)
+{: .fs-5 .fw-400 }
+
+This example demonstrates how to define the shape (structure) of the Jacobian matrix.
+I.e., instead of providing the full analytic Jacobian (or not providing it at all, which is slow if the system is big), the user can specify the positions of non-zero elements in the Jacobian.
+The solver will use automatic differentiation for the specified elements only.
+This works (nearly) as fast as the analytic Jacobian without requiring the user to differentiate the vector function manually.
+
+## Checking user-defined Jacobian
+
+Jacobian matrix checking source file example: [jacobian_compare.cpp](https://github.com/dae-cpp/dae-cpp/blob/master/examples/jacobian_compare/jacobian_compare.cpp)
+{: .fs-5 .fw-400 }
+
+In this example, we do not solve any DAEs. Instead, we define a simple vector function, the corresponding Jacobian matrix, and then we use a built-in helper class `JacobianCompare` to compare our manually derived Jacobian with the one computed algorithmically from the vector function.
+We will make a few mistakes in the analytic Jacobian on purpose to see what information `JacobianCompare` can provide.

docs/index.md

@@ -4,7 +4,7 @@ layout: home
 nav_order: 1
 ---
 
-![version](https://img.shields.io/badge/version-2.0.1-blue)
+![version](https://img.shields.io/badge/version-2.1.0-blue)
 
 <p align="center">
 <img src="../assets/images/logo.png" alt="dae-cpp logo" width="250"/>