functions in dawson.i - m

             merge_n(val1,mask1, val2,mask2, ...)  
 
    return array with shape of MASKi (which must all have same shape)  
    and values VALi where MASKi is true.  Unspecified values will be  
    zero; the data type of the result is the data type of the first  
    non-nil VALi.  Each VALi must be a 1D array of length sum(MASKi!=0).  
interpreted function, defined at i/dawson.i   line 161