feat: aggiunge salvataggio CSV soluzione FDM in results/fdm/

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

fdm/app.py

@@ -3,7 +3,7 @@ import os
 
 sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
 
-from fdm.solver import solve
+from fdm.solver import solve, save_csv
 from fdm.visualizer import visualize_fdm
 
 
@@ -26,10 +26,11 @@ def main_menu():
         print("-" * 30)
         print("1. Risolvi")
         print("2. Visualizza")
+        print("3. Salva CSV")
         print("0. Esci")
         print("-" * 30)
 
-        choice = input("Select an option (0-2): ").strip()
+        choice = input("Select an option (0-3): ").strip()
 
         if choice == "1":
             T, x_vals, t_vals = solve()
@@ -42,6 +43,12 @@ def main_menu():
             else:
                 visualize_fdm(T, x_vals, t_vals)
 
+        elif choice == "3":
+            if T is None:
+                print("Eseguire prima l'opzione 1.")
+            else:
+                save_csv(T, x_vals, t_vals, "results/fdm/fdm_solution.csv")
+
         elif choice == "0":
             print("Uscita.")
             sys.exit(0)

fdm/solver.py

@@ -14,6 +14,7 @@ Returns T_matrix of shape (NX, NT).
 import sys
 import os
 import numpy as np
+import pandas as pd
 
 sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
 import config
@@ -85,3 +86,16 @@ def solve():
         T_matrix[:, n + 1] = T_cur
 
     return T_matrix, x_vals, t_vals
+
+
+def save_csv(T_matrix, x_vals, t_vals, path: str) -> None:
+    """Save FDM solution to CSV with columns: x, t, T."""
+    xs, ts = np.meshgrid(x_vals, t_vals, indexing="ij")
+    df = pd.DataFrame({
+        "x": xs.ravel(),
+        "t": ts.ravel(),
+        "T": T_matrix.ravel(),
+    })
+    os.makedirs(os.path.dirname(os.path.abspath(path)), exist_ok=True)
+    df.to_csv(path, index=False)
+    print(f"Salvato: {path}  ({len(df)} righe)")