[Diff since v9.31.0](SciML/ModelingToolkit.jl@v9.31.0...v9.32.0)

**Merged pull requests:**
- support JumpProblems over ODEProblems (SciML#2946) (@isaacsas)

[Diff since v9.30.1](SciML/ModelingToolkit.jl@v9.30.1...v9.31.0)

**Merged pull requests:**
- fix: fix initialization with defaults dependent on indepvar (SciML#2820) (@AayushSabharwal)
- add an example to IO docs (SciML#2926) (@baggepinnen)
- fix: fix replace with array dependent parameters (SciML#2933) (@AayushSabharwal)
- Flatten for complex (SciML#2935) (@contradict)
- Disallow duplicate names (SciML#2938) (@contradict)
- normalize operating point user input (SciML#2939) (@baggepinnen)
- fix: fix vectorization of array variables with inputs (SciML#2940) (@AayushSabharwal)
- Fix Latex tests to use new upstream equation equality aligning (SciML#2942) (@hersle)
- Add DummyDerivativeSummary debuginfo (SciML#2943) (@YingboMa)
- Experimental variable filtering in dummy derivative (SciML#2944) (@YingboMa)

**Closed issues:**
- Cannot (re)make problems with defaults involving the independent parameter (SciML#2799)
- Possible to create system where a parameter and variable have the same name (SciML#2883)
- Missing whitespace in documentation equations (SciML#2894)
- Cannot use `Complex` equation in `@mtkmodel` (SciML#2895)
- Warning: Internal error (SciML#2920)
- Replacing tunables of dependent parameter vector fails (SciML#2932)

[Diff since v9.30.0](SciML/ModelingToolkit.jl@v9.30.0...v9.30.1)

**Merged pull requests:**
- Make default value units consistent (SciML#2898) (@contradict)
- Fix README example (SciML#2930) (@hersle)
- update JumpSystem for auto-alg support (SciML#2931) (@isaacsas)
- Add documentation for `irreducible` metadata (SciML#2936) (@contradict)
- Extend state priority to all its derivative chains in DD (SciML#2937) (@YingboMa)

**Closed issues:**
- High Level example 2 error: ExtraVariablesSystemException: The system is unbalanced (SciML#2925)

[Diff since v9.29.0](SciML/ModelingToolkit.jl@v9.29.0...v9.30.0)

**Merged pull requests:**
- Support more of the SciMLBase events API (SciML#2911) (@BenChung)
- rewrite optimization tutorial (SciML#2916) (@ArnoStrouwen)
- fix some cosmetics in docs (SciML#2921) (@baggepinnen)
- fix: fix downstream indexing tests (SciML#2927) (@AayushSabharwal)

**Closed issues:**
- Event trigger directionality (SciML#1715)
- No documented way to set rootfind=RightRootFind in continuous Event. (SciML#2351)

[Diff since v9.28.0](SciML/ModelingToolkit.jl@v9.28.0...v9.29.0)

**Merged pull requests:**
- ci: standardise workflows using SciML's reusable workflows (SciML#2695) (@thazhemadam)
- Getting started doc rewrite (SciML#2903) (@ArnoStrouwen)
- refactor: turn tunables portion into a Vector{T} (SciML#2908) (@AayushSabharwal)
- Delete mo.diff (SciML#2913) (@ChrisRackauckas)
- Detect cases where there's fewer brownians than equations, but noise still 'diagonal' (SciML#2914) (@MasonProtter)
- rewrite nonlinear solve tutorial (SciML#2915) (@ArnoStrouwen)
- add docs for input-output handling (SciML#2918) (@baggepinnen)

**Closed issues:**
- Fix broken indexing tests (SciML#2696)

[Diff since v9.27.0](SciML/ModelingToolkit.jl@v9.27.0...v9.28.0)

**Merged pull requests:**
- fix: fix some linearization bugs (SciML#2912) (@AayushSabharwal)

**Closed issues:**
- undefvar and bounds error in linearization_function (SciML#2907)

[Diff since v9.26.0](SciML/ModelingToolkit.jl@v9.26.0...v9.27.0)

**Merged pull requests:**
- feat: implement new discrete saving functionality (SciML#2728) (@AayushSabharwal)
- Add tests of various features (SciML#2806) (@TorkelE)
- fix: allow vector defaults in `@mtkmodel` (SciML#2830) (@ven-k)
- fix: fix edge cases with metadata dumping, add tests (SciML#2836) (@AayushSabharwal)
- Rename `@mtkmodel`... docs and add a section describing `@mtkbuild`  (SciML#2890) (@ven-k)
- fix: fix remaking scalarized array parameters with non-scalarized symbolic map (SciML#2897) (@AayushSabharwal)
- CompatHelper: bump compat for SymbolicUtils to 3 for package docs, (keep existing compat) (SciML#2901) (@github-actions[bot])
- Use `subs_constants` in `generate_control_function` (SciML#2904) (@aml5600)

**Closed issues:**
- `remake` fails with `ERROR: ArgumentError: ... is neither an observed nor an unknown variable.` (SciML#2757)
- Cannot provide vector parameter values to `remake` for scalarised system (SciML#2804)
- Cannot provide default value for array parameter (SciML#2810)
- Cannot simulate SDEs with static array parameters/initial conditions (SciML#2851)
- Array-valued parameters are not interpreted correctly when creating ODESystem (SciML#2876)
- `@constants` not defined in `generate_control_function` output (SciML#2896)

[Diff since v9.25.0](SciML/ModelingToolkit.jl@v9.25.0...v9.26.0)

**Merged pull requests:**
- document the `fully_determined` kwarg to structural_simplify (SciML#2880) (@MasonProtter)
- Detect diagonal noise in `SDESystem` (SciML#2882) (@MasonProtter)
- Pass down documented kwargs in structural_simplifiy (SciML#2885) (@ChrisRackauckas)
- fix: create specialized `isdiag` for symbolics in noise matrix (SciML#2886) (@AayushSabharwal)
- feat: allow specifying `nothing` as default value to skip it (SciML#2887) (@AayushSabharwal)

**Closed issues:**
- Diagonal noise not detected during lowering of `System` with `@brownian` variables (SciML#2490)
- `@discrete_events` or `@continuous_events` not working with acausal modeling framework (SciML#2849)
- fix requirement for SDESystems to take Num inputs (SciML#2868)

[Diff since v9.24.0](SciML/ModelingToolkit.jl@v9.24.0...v9.25.0)

**Merged pull requests:**
- Extend initialization equations (SciML#2846) (@hersle)
- Handle modelingtoolkitize for nonlinearleastsquaresproblem (SciML#2847) (@ChrisRackauckas)
- Left-to-right expand observed equations into defaults during initialization (SciML#2861) (@hersle)
- Create independent variables with @independent_variables (SciML#2862) (@hersle)
- Capture observed dependence on unknowns in simplified nonlinear systems (SciML#2863) (@hersle)
- Error missing defaults (SciML#2864) (@hersle)
- Extend metadata (SciML#2867) (@hersle)
- refactor: avoid substitute warning when not needed (SciML#2869) (@SebastianM-C)
- Add more documentation (SciML#2871) (@hersle)
- Export more functions relating to system initialization (SciML#2872) (@hersle)
- Restore error when unknowns in the initialization system don't have guesses  (SciML#2877) (@hersle)
- Some repo cleanup (SciML#2878) (@ChrisRackauckas)
- Allow for setting fully_determined=true in initialization (SciML#2879) (@ChrisRackauckas)

**Closed issues:**
- Duplicate Global Parameters (SciML#992)
- Documentation for `equations, equations, full_equations` (SciML#1822)
- Some `ODESystem` fields such as `metadata` are lost when using the `extend` function (SciML#2502)
- Allow altering a symbolic parameter default value after creation. (SciML#2650)
- Add NonlinearLeastSquaresProblem dispatch for modelingtoolkitize (SciML#2669)
- Error when plotting multiple (not single) observable in Symbol form (SciML#2739)
- Custom independent variable leads to underdetermined initialization system (SciML#2818)
- Precompiling MTK when `--depwarn=yes` or `--depwarn=true` causes deprecation warning (SciML#2827)
- extend() does not pass on initialization equations (SciML#2845)
- testing against Julia 1.6 LTS dropped (SciML#2854)
- Subsystem not namespaced when substituted coefficient is 1 (SciML#2855)
- Cannot initialize well-defined ODE with defaults (SciML#2859)
- Helpful error for missing guesses has disappeared (SciML#2873)

[Diff since v9.23.0](SciML/ModelingToolkit.jl@v9.23.0...v9.24.0)

**Merged pull requests:**
- Better error throwing on ill-formed SDESystems (SciML#2833) (@ChrisRackauckas)
- fix: fix deepcopy for SteadyStateProblem (SciML#2840) (@AayushSabharwal)

**Closed issues:**
- Regression: Cannot deepcopy `SteadyStateProblem` (SciML#2837)