Extending a single-prec array with double-prec complex throws bad_cast.

[John W. Eaton]

On  1-Mar-2009, Jason Riedy wrote:

| The following terminates Octave's tip with a std::bad_cast from 
| OPERATORS/op-fcm-fcm.cc:187:
|   octave -q --eval 'y = zeros (10, 1, "single"); x = ones (10, 1) + I (); y(:,2) = x;'
| 
| Via gdb, the next level up where the values aren't optimized out
| is octave_base_value::numeric_assign at ov-base.cc:1151. The rhs
| appears to be of type "unknown", so the real error may have
| occurred somewhere else.
| 
| Note that assigning to y(:,1) or using concatenation both work.

I checked in the following change.

  http://hg.savannah.gnu.org/hgweb/octave/rev/ac8f5a159c2c

Thanks,

jwe