[GiNaC-devel] [GiNaC-list] multiplying a matrix with 0 makes it become a scalar 0

[Jens Vollinga]

Dear all,

concerning this question from the GiNaC-list:

dummy-address at web.de schrieb:
> cout << "(3*blah).evalm(): " << (3*blah).evalm() << endl;
> // output:
> //    [[3*a], [3*b], [3*c]]
> 
> cout << "0*blah: " << 0*blah << endl;
> // output:
> //    0

seems to be a bug, and a rather old one (2000/2001).

My only idea at the moment is to check explicitly for matrices in the 
epvector (mul.cpp lines 428-430) which is kind of stupid. Or we could 
introduce another info_flag for non-scalar objects (set by matrix then) 
and check for that flag? Any other ideas?

Regards,
Jens