diff -ur quaternion.orig/src/is_real_array.cc quaternion/src/is_real_array.cc
--- quaternion.orig/src/is_real_array.cc	2019-01-02 13:53:40.766144030 -0500
+++ quaternion/src/is_real_array.cc	2019-01-02 13:54:35.459444478 -0500
@@ -46,8 +46,8 @@
         {
             // args(i).ndims () should be always >= 2
             if (args(i).ndims () < 2
-                || ! ((args(i).is_numeric_type () && args(i).is_real_type ())
-                      || args(i).is_bool_type ()))
+                || ! ((args(i).isnumeric () && args(i).isreal ())
+                      || args(i).islogical ()))
             {
                 retval = false;
                 break;