add method to add new columns to phase screens

aotools/turbulence/infinitephasescreen.py

@@ -193,7 +193,7 @@ def get_new_row(self):
 
         new_row.shape = (1, self.nx_size)
         return new_row
-
+    
     def add_row(self):
         """
         Adds a new row to the phase screen and removes old ones.
@@ -205,6 +205,23 @@ def add_row(self):
 
         return self.scrn
 
+    def get_new_col(self):
+        random_data = self._R.normal(0, 1, size=self.nx_size)
+
+        stencil_data = self._scrn.T[(self.stencil_coords[:, 0], self.stencil_coords[:, 1])]
+        new_row = self.A_mat.dot(stencil_data) + self.B_mat.dot(random_data)
+
+        new_row.shape = (1, self.nx_size)
+        return new_row
+
+    def add_col(self):
+        new_col = self.get_new_col()
+        self._scrn = numpy.append(new_col.T, self._scrn, axis=1)[:self.nx_size, :self.stencil_length]
+        return self.scrn
+
+
+
+
     @property
     def scrn(self):
         """