clear all
st_single_double = 'single';
abc = zeros([10,10],st_single_double);
st_single_double = 'double';
efg = zeros([10,10],st_single_double);
whos
  Name                   Size            Bytes  Class     Attributes

  abc                   10x10              400  single              
  efg                   10x10              800  double              
  st_single_double       1x6                12  char