src/overload/row-operns.lisp

   1
   2 (defun over-det (a)
   3   (if (= (mtrix-dimdom a) (mtrix-dimcodom a))
   4     (det (mtrix-elems a))
   5     (throw 'over-ex "Determinants only work with square matrices.")))
   6
   7 (defun over-r-ef (&rest args)
   8   (let ((a (apply #'over-cat args)))
   9     (make-mtrix-like
  10       a (r-ef (mtrix-elems a)))))
  11
  12 (defun over-rr-ef (&rest args)
  13   (let ((a (apply #'over-cat args)))
  14     (make-mtrix-like
  15       a (rr-ef (mtrix-elems a)))))
  16
  17 (defmethod over-multv-inverse ((a mtrix))
  18   (when (zerop (over-det a))
  19     (throw 'over-ex "Determinant is zero, no inverse exists."))
  20   (make-mtrix-like
  21     a (mtrix-inverse (mtrix-elems a))))
  22
  23 ;V Raise matrix /a/ to exponent /b/.V
  24 (defmethod expt2n ((a mtrix) (b integer))
  25   ;V Matrix must be square.V
  26   (unless (= (mtrix-dimdom a)
  27              (mtrix-dimcodom a))
  28     (throw 'over-ex "Only square matrices can be raised to exponents."))
  29   ;V If negative power, raise inverse V
  30   ;V of /a/ to negative /b/ power.    V
  31   (when (minusp b)
  32     (setq a (over-multv-inverse a)
  33           b (- b)))
  34   ;V When /b/ is zero, return the identity matrix.V
  35   (if (zerop b)
  36     (make-mtrix
  37       :dimdom (mtrix-dimdom a)
  38       :dimcodom (mtrix-dimdom a)
  39       :elems (mtrix-square-identity (mtrix-dimdom a)))
  40     (loop :repeat b
  41           :for c = a :then (mult2n a c)
  42           :finally (return c))))
  43