src/overload/row-operns.lisp

   1
   2 (in-package :lineal.overload)
   3
   4 (defun over-det (a)
   5   (if (= (mtrix-dimdom a) (mtrix-dimcodom a))
   6     (det (mtrix-elems a))
   7     (throw 'over-ex "Determinants only work with square matrices.")))
   8
   9 (defun over-r-ef (&rest args)
  10   (let ((a (apply #'over-cat args)))
  11     (make-mtrix-like
  12       a (r-ef (mtrix-elems a)))))
  13
  14 (defun over-rr-ef (&rest args)
  15   (let ((a (apply #'over-cat args)))
  16     (make-mtrix-like
  17       a (rr-ef (mtrix-elems a)))))
  18
  19 (defmethod over-multv-inverse ((a mtrix))
  20   (when (zerop (over-det a))
  21     (throw 'over-ex "Determinant is zero, no inverse exists."))
  22   (make-mtrix-like
  23     a (mtrix-inverse (mtrix-elems a))))
  24
  25 ;V Raise matrix /a/ to exponent /b/.V
  26 (defmethod expt2n ((a mtrix) (b integer))
  27   ;V Matrix must be square.V
  28   (unless (= (mtrix-dimdom a)
  29              (mtrix-dimcodom a))
  30     (throw 'over-ex "Only square matrices can be raised to exponents."))
  31   ;V If negative power, raise inverse V
  32   ;V of /a/ to negative /b/ power.    V
  33   (when (minusp b)
  34     (setq a (over-multv-inverse a)
  35           b (- b)))
  36   ;V When /b/ is zero, return the identity matrix.V
  37   (if (zerop b)
  38     (make-mtrix
  39       :dimdom (mtrix-dimdom a)
  40       :dimcodom (mtrix-dimdom a)
  41       :elems (mtrix-square-identity (mtrix-dimdom a)))
  42     (loop :repeat b
  43           :for c = a :then (mult2n a c)
  44           :finally (return c))))
  45