Make operators do smarter sparse conversions on permutation matrices. * Sparse.cc (Sparse<T>::Sparse): New templated ctor, plus two instantiations. * Sparse.h (Sparse<T>): Declare new ctor. * MSparse.h (MSparse): Give this class a PermMatrix ctor. * boolSparse.h (BoolSparseMatrix): Ditto. * dSparse.cc: Refactor PermMatrix ctor, moved into common parent class. * dSparse.h (SparseMatrix): Ditto. * op-pm-sm.cc: Declare and install smarter permutation matrix operators. * ov-perm.cc (octave_perm_matrix): Declare new virtual function override. * ov-perm.cc (sparse_bool_matrix_value): Override this virtual function.

--- a/liboctave/Sparse.h
+++ b/liboctave/Sparse.h
@@ -41,6 +41,7 @@
 #include "oct-mem.h"
 
 class idx_vector;
+class PermMatrix;
 
 // Two dimensional sparse class.  Handles the reference counting for
 // all the derived classes.
@@ -195,6 +196,10 @@
     : rep (new typename Sparse<T>::SparseRep (nr, nc, nz)),
       dimensions (dim_vector (nr, nc)) { }
 
+  // Both SparseMatrix and SparseBoolMatrix need this ctor, and this
+  // is their only common ancestor.
+  explicit Sparse (const PermMatrix& a);
+
   // Type conversion case. Preserves capacity ().
   template <class U>
   Sparse (const Sparse<U>& a)