update readme for latest updates for green-grids version checks.

README.md

@@ -47,6 +47,7 @@ Class has to be parametrized with user defined `Dyson` type. `Dyson` publicly de
 - `solve(G&, Sigma1&, Sigma_tau&)` - for a given self-energies
 - `diff(G&, Sigma1&, Sigma_tau&)` - computes convergence creteria
 - `dump_iteration(int iter, const std::string&f)` - store additional data into a results file `f` for a given iteration `iter`.
+- `const std::string& get_grids_version() const` - returns either the version of IR/Chebyshev transformation grid files if [`green-grids`](https://github.com/Green-Phys/green-grids.git) is used, otherwise, it should return `green::grids::GRIDS_MIN_VERSION` as a placeholder.
 
 The method `solve` needs four parameters:
 
@@ -79,6 +80,20 @@ public:
   }
   double diff(const G& g, const Sigma1& sigma1, const Sigma_tau& sigma_tau) { return _diff; }
   void   dump_iteration(size_t iter, const std::string& result_file){};
+
+  /**
+   * @brief Returns a dummy min grids version used in IR / Chebyshev Fourier transformations
+   * NOTE:  Ideally, the Dyson solver depends on green-grids for IR / Chebyshev Fourier transformation;
+   *        In that case, define a class variable:
+   * 
+   *        green::grids::transformer_t _ft;
+   * 
+   *        which is initialized as _ft(p)  -- p being the green::params::params type
+   *        And then, the function get_grids_version() should return
+   * 
+   *        _ft.get_version();
+   */
+  const std::string & get_grids_version() const { return green::grids::GRIDS_MIN_VERSION; }
 };
 
 // define solver class