;文字列 "x" を 倍精度実数値 double-float に変換する
(defun to_f (x)
  (if (equal x nil) (setq x "0"))
  (if (listp x)
      (mapcar #'to_f x)
      (progn
        (if (typep x 'double-float)
            x
            (progn
              (if (stringp x) nil (setq x (write-to-string x)))
              (if (search "e" x)
                  (progn
                    (setq s (search "e" x))
                    (read-from-string
                      (concatenate 'string
                        (subseq x 0 s) "d" (subseq x (+ 1 s) (length x)))
                    )
                  ) ;progn (search "e" x)
                  (if (search "d" x)
                      x
                      (read-from-string
                        (concatenate 'string x "d0")
                      )
                  )
              )
            ) ;progn (typep x 'double-float)
        )
      ) ;progn (listp x)
  )
)