Execution of "size(sprand(5e4,5e4,5e-4),'*')" suffers from Integer Overflow

[rdbyk]

--> size(sprand(5e4,5e4,5e-4),'*')
 ans  =

  -1.795D+09

probably related to #766

[rdbyk]

A warning should be raised to indicate, that the result might be wrong!