Index: /issm/trunk-jpl/src/c/classes/Elements/TetraRef.cpp
===================================================================
--- /issm/trunk-jpl/src/c/classes/Elements/TetraRef.cpp	(revision 17405)
+++ /issm/trunk-jpl/src/c/classes/Elements/TetraRef.cpp	(revision 17406)
@@ -301,5 +301,15 @@
 	IssmDouble z4=xyz_list[3*3+2];
 
-	_error_("Not implemented yet");
+	J[NDOF3*0+0] = x2-x1;
+	J[NDOF3*1+0] = y2-y1;
+	J[NDOF3*2+0] = z2-z1;
+
+	J[NDOF3*0+1] = x3-x1;
+	J[NDOF3*1+1] = y3-y1;
+	J[NDOF3*2+1] = z3-z1;
+
+	J[NDOF3*0+2] = x4-x1;
+	J[NDOF3*1+2] = y4-y1;
+	J[NDOF3*2+2] = z4-z1;
 }
 /*}}}*/