make diag (x, m, n) return a proper diagonal matrix object (bug #36099) * Array.h, Array.cc (Array<T>::diag (octave_idx_type, octave_idx_type) const): New function. * CMatrix.h, CMatrix.cc (ComplexMatrix::diag (octave_idx_type, octave_idx_type) const): New function. * dMatrix.h, dMatrix.cc (Matrix::diag (octave_idx_type, octave_idx_type) const): New function. * fCMatrix.h, fCMatrix.cc (FloatComplexMatrix::diag (octave_idx_type, octave_idx_type) const): New function. * fMatrix.h, fMatrix.cc (FloatMatrix::diag (octave_idx_type, octave_idx_type) const): New function. * CNDArray.cc, CNDArray.h (ComplexNDArray::diag (octave_idx_type, octave_idx_type) const): New forwarding function. * boolNDArray.cc, boolNDArray.h (boolNDArray::diag (octave_idx_type, octave_idx_type) const): New forwarding function. * chNDArray.cc, chNDArray.h (charNDArray::diag (octave_idx_type, octave_idx_type) const): New forwarding function. * dNDArray.cc, dNDArray.h (NDArray::diag (octave_idx_type, octave_idx_type) const): New forwarding function. * fCNDArray.cc, fCNDArray.h (FloatComplexNDArray::diag (octave_idx_type, octave_idx_type) const): New forwarding function. * fNDArray.cc, fNDArray.h (FloatNDArray::diag (octave_idx_type, octave_idx_type) const): New forwarding function. * intNDArray.cc, intNDArray.h (intNDArray<T>::diag (octave_idx_type, octave_idx_type) const): New forwarding function. * Cell.cc, Cell.h (Cell::diag (octave_idx_type, octave_idx_type) const): New function. * ov.h (octave_value::diag (octave_idx_type, octave_idx_type)): New function. * ov-base.h, ov-base.cc (octave_base_value::diag (octave_idx_type, octave_idx_type) const): New virtual function and default implementation. * ov-base-mat.h (octave_base_matrix<T>::diag (octave_idx_type, octave_idx_type) const): New function. * ov-base-scalar.cc, ov-base-scalar.h (octave_base_scalar<T>::diag (octave_idx_type, octave_idx_type)): New function. * ov-complex.cc, ov-complex.h (octave_complex::diag (octave_idx_type, octave_idx_type) const): New function. * ov-cx-mat.cc, ov-complex.h (octave_complex_matrix::diag (octave_idx_type, octave_idx_type) const): New function. * ov-float.cc, ov-float.h (octave_float_scalar::diag (octave_idx_type, octave_idx_type) const): New function. * ov-flt-complex.cc, ov-flt-complex.h (octave_float_complex::diag (octave_idx_type, octave_idx_type) const): New function. * ov-flt-cx-mat.cc, ov-flt-cx-mat.h (octave_float_complex_matrix::diag (octave_idx_type, octave_idx_type) const): New function. * ov-flt-re-mat.cc, ov-flt-re-mat.h (octave_float_matrix::diag (octave_idx_type, octave_idx_type) const): New function. * ov-range.cc, ov-range.h (octave_range::diag (octave_idx_type, octave_idx_type) const): New function. * ov-re-mat.cc, ov-re-mat.h (octave_matrix::diag (octave_idx_type, octave_idx_type) const): New function. * ov-scalar.cc, ov-scalar.h (octave_scalar::diag (octave_idx_type, octave_idx_type) const): New function. * data.cc (Fdiag): Use two-arg octave_value::diag method for dispatching. New tests.

--- a/src/data.cc
+++ b/src/data.cc
@@ -1281,11 +1281,14 @@
   else if (nargin == 3)
     {
       octave_value arg0 = args(0);
-      if (arg0.ndims () == 2 && (args(0).rows () == 1 || args(0).columns () == 1))
+
+      if (arg0.ndims () == 2 && (arg0.rows () == 1 || arg0.columns () == 1))
         {
-          octave_idx_type m = args(1).int_value (), n = args(2).int_value ();
+          octave_idx_type m = args(1).int_value ();
+          octave_idx_type n = args(2).int_value ();
+
           if (! error_state)
-            retval = arg0.diag ().resize (dim_vector (m, n), true);
+            retval = arg0.diag (m, n);
           else
             error ("diag: invalid dimensions");
         }
@@ -1341,7 +1344,15 @@
 %!error diag (ones (2), 3, 3)
 %!error diag (1:3, -4, 3)
 
- */
+%!assert (diag (1, 3, 3), diag ([1, 0, 0]))
+%!assert (diag (i, 3, 3), diag ([i, 0, 0]))
+%!assert (diag (single (1), 3, 3), diag ([single(1), 0, 0]))
+%!assert (diag (single (i), 3, 3), diag ([single(i), 0, 0]))
+%!assert (diag ([1, 2], 3, 3), diag ([1, 2, 0]))
+%!assert (diag ([1, 2]*i, 3, 3), diag ([1, 2, 0]*i))
+%!assert (diag (single ([1, 2]), 3, 3), diag (single ([1, 2, 0])))
+%!assert (diag (single ([1, 2]*i), 3, 3), diag (single ([1, 2, 0]*i)))
+*/
 
 DEFUN (prod, args, ,
   "-*- texinfo -*-\n\