Merge pull request #896 from pybamm-team/issue-858-ddt

#858 add changelog

CHANGELOG.md

@@ -2,9 +2,14 @@
 
 ## Features
 
--   Added functionality to broadcast to edges ([#891](https://github.com/pybamm-team/PyBaMM/pull/891))
+-   Add new symbols `VariableDot`, representing the derivative of a variable wrt time, 
+    and `StateVectorDot`, representing the derivative of a state vector wrt time 
+    ([#858](https://github.com/pybamm-team/PyBaMM/issues/858))
+-   Added functionality to broadcast to edges 
+    ([#891](https://github.com/pybamm-team/PyBaMM/pull/891))
 -   Added additional notebooks showing how to create and compare models ([#877](https://github.com/pybamm-team/PyBaMM/pull/877))
--   Added `Minimum`, `Maximum` and `Sign` operators ([#876](https://github.com/pybamm-team/PyBaMM/pull/876))
+-   Added `Minimum`, `Maximum` and `Sign` operators 
+    ([#876](https://github.com/pybamm-team/PyBaMM/pull/876))
 -   Added a search feature to `FuzzyDict` ([#875](https://github.com/pybamm-team/PyBaMM/pull/875))
 -   Add ambient temperature as a function of time ([#872](https://github.com/pybamm-team/PyBaMM/pull/872))
 -   Added `CasadiAlgebraicSolver` for solving algebraic systems with CasADi ([#868](https://github.com/pybamm-team/PyBaMM/pull/868))