 Usage:  desc=descriptive(x{,xvars})  
 
 Input:

  x                      n x p matrix, the columns correspond to the 
                         variables. (x may contain NaN, Inf or -Inf.) 
                         
  xvars                  optional, p x 1 string vector, variable names. 
                         
 Output:

  desc                   string output, containing table of descriptive 
                         statistics. 
                         
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(C) MD*TECH Method and Data Technologies, 17.8.2000
