 Usage:  bp = grhist (x, {d, {o, {col}}})  
 
 Input:

  xr                     n x 1 vector 
                         
  d                      scalar binwidth 
                         
  o                      scalar origin 
                         
  col                    color 
                         
 Output:

  bp                     composed graphical object 
                         
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(C) MD*TECH Method and Data Technologies, 17.8.2000
