Fix bug in construction of eigenvector matrix

Eigenvectors were not in columns - only obvious when looking at ellipsoid with axes not aligned with viewing axes.

qt/python/mantidqt/widgets/sliceviewer/peaksviewer/representation/ellipsoid.py

@@ -14,6 +14,9 @@ import numpy.linalg as linalg
 from .alpha import compute_alpha
 from .painter import Painted
 
+import pydevd_pycharm
+pydevd_pycharm.settrace('debug_host', port=44444, stdoutToServer=True, stderrToServer=True, suspend=False)
+
 
 class EllipsoidalIntergratedPeakRepresentation():
     """Provide methods to display a representation of a slice through an
@@ -193,7 +196,7 @@ def calculate_ellipsoid_matrix(axis_a, axis_b, axis_c, a, b, c, transform):
     # transformation matrix (inverse gives transform from MD to view basis)
     R = np.vstack((transform((1, 0, 0)), transform((0, 1, 0)), transform((0, 0, 1))))
     # matrix with eigenvectors (in view basis) in columns
-    axes_dir = linalg.inv(R) @ np.vstack((axis_a, axis_b, axis_c))
+    axes_dir = linalg.inv(R) @ np.hstack((axis_a[:,None], axis_b[:,None], axis_c[:,None]))
 
     return axes_dir @ axes_lengths @ np.transpose(axes_dir)