/*
 *  call-seq:
 *     Dvector.read_row(filename, row=1, dvector=nil)  ->  dvector
 *
 *  This routine reads a row of numbers from the named file.
 *  The _row_ argument determines which line of the file to read, starting at 1 for the first line.
 *  If the _dvector_ argument is <code>nil</code>, a new Dvector is allocated to hold the row of numbers.
 *  Otherwise, the contents of _dvector_ are replaced by the numbers from the line in the file.
 *  
 */ 
VALUE dvector_read_row(int argc, VALUE *argv, VALUE klass) {