functions in msort.i - m

             msort(x1, x2, x3, ...)  
 
     returns an index list which sorts the array X1 into increasing  
     order.  Where X1 values are equal, the list will sort X2 into  
     increasing order.  Where both X1 and X2 are equal, X3 will be  
     in increasing order, and so on.  Finally, where all of the keys  
     are equal, the returned list will leave the order unchanged  
     from the input keys.  
     The Xi may be numbers or strings (e.g.- X1 could be an integer  
     while X2 was a string, and X3 was a real).  The Xi must all be  
     conformable, and each dimension of X1 must be as large as the  
     corresponding dimension of any otehr Xi.  
     Hence, msort(x) will return the same list as sort(x), except  
     where the values of x are equal, in which case msort leaves  
     the order unchanged, while sort non-deterministically permutes  
     equal elements.  This feature may cost a factor of two in speed,  
     so don't use it unless you really need it.  In general, msort  
     will call sort up to twice per input argument.  
interpreted function, defined at i/msort.i   line 10  

             msort_rank(x)  
             msort_rank(x, list)  
 
     returns a list of longs the same size and shape as X, whose  
     values are the "rank" of the corresponding element of X among  
     all the elements of X -- the smallest element has rank 0 and  
     the largest has the largest rank, which is equal to one less  
     than the number of distinct values in the array X.  
     If LIST is present, it is set to the order list returned by  
     sort(x(*)).  
interpreted function, defined at i/msort.i   line 55