From 87ac3e5aba05140bd692635a104ecee33ee28459 Mon Sep 17 00:00:00 2001
From: Stephan Rave <stephanrave@uni-muenster.de>
Date: Thu, 24 Aug 2023 09:38:34 +0200
Subject: [PATCH] hack NumpyVectorArray.axpy into using dger

---
 src/pymor/vectorarrays/numpy.py | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/src/pymor/vectorarrays/numpy.py b/src/pymor/vectorarrays/numpy.py
index d55579ff50..a79b5cf820 100644
--- a/src/pymor/vectorarrays/numpy.py
+++ b/src/pymor/vectorarrays/numpy.py
@@ -112,6 +112,13 @@ def axpy(self, alpha, x, ind, xind):
             self._array = self._array.astype(dtype)
 
         if type(alpha) is np.ndarray:
+            if len(B) == 1:
+                from scipy.linalg.blas import dger
+                a = self._array[ind]
+                if len(a) == 0:
+                    return
+                dger(1., B.ravel(), alpha, a=a.T, overwrite_x=0, overwrite_y=0, overwrite_a=1)
+                return
             alpha = alpha[:, np.newaxis]
 
         if isinstance(alpha, Number):