BUG: Fixed issue/37

See #37

As noted by the reported, the logic of _remove_axes was not right.
We always have to remove the last axis (since _cook_nd_args rearranges
it that way), but upon remove of the axis, we have to decrease all
the axis higher than the pivot by one, since we take part at the pivot.

Author: oleksandr-pavlyk

mkl_fft/_pydfti.pyx

@@ -878,7 +878,9 @@ def _remove_axis(s, axes, axis_to_remove):
     a2r = lens + axis_to_remove if axis_to_remove < 0 else axis_to_remove
 
     ss = s[:a2r] + s[a2r+1:]
-    aa = axes_normalized[:a2r] + tuple(ai - 1 for ai in axes_normalized[a2r+1:])
+    pivot = axes_normalized[a2r]
+    aa = tuple(ai if ai < pivot else ai - 1 for ai in axes_normalized[:a2r]) + \
+         tuple(ai if ai < pivot else ai - 1 for ai in axes_normalized[a2r+1:])
     return ss, aa
 
 
@@ -938,7 +940,7 @@ def rfftn_numpy(x, s=None, axes=None):
             ss[-1] = a.shape[la]
             a = _fix_dimensions(a, tuple(ss), axes)
         if len(set(axes)) == len(axes) and len(axes) == a.ndim and len(axes) > 2:
-            ss, aa = _remove_axis(s, axes, la)
+            ss, aa = _remove_axis(s, axes, -1)
             ind = [slice(None,None,1),] * len(s)
             for ii in range(a.shape[la]):
                 ind[la] = ii