Update README and improve numerical handling in scipy_reference.py

- Removed redundant phrasing in the README to streamline the description of MicroMode.
- Enhanced the handling of initial vectors in the _real_arpack_problem_if_close function to ensure proper casting to real values, improving numerical stability.

Author: QuentinWach

README.md

@@ -1,8 +1,6 @@
 # micromode
 
 An **electromagnetic mode solver** using the **[FDFD method](https://en.wikipedia.org/wiki/Finite-difference_frequency-domain_method)** on a **[rectilinear Yee-grid](https://en.wikipedia.org/wiki/Finite-difference_time-domain_method)**.
-MicroMode is a transparent, grid-first SciPy mode solver for rasterized
-photonics workflows.
 
 ```bash
 pip install micromode

python/micromode/scipy_reference.py

@@ -664,7 +664,7 @@ def _real_arpack_problem_if_close(matrix, initial_vector: np.ndarray | None, gue
     # If the complex part is numerical noise, cast to real to avoid SciPy's
     # ComplexWarning path and improve reproducibility.
     if np.max(np.abs(matrix_imag)) <= 1e-14 * matrix_scale and guess_is_real:
-        real_vector = None if initial_vector is None else np.asarray(initial_vector.real, dtype=float)
+        real_vector = None if initial_vector is None else np.asarray(np.real(initial_vector), dtype=float)
         return matrix.real.astype(float), real_vector, float(guess.real)
     return matrix, initial_vector, guess