Function: calc-explain-units-rec

calc-explain-units-rec is a byte-compiled function defined in calc-units.el.gz.

Signature

(calc-explain-units-rec EXPR POW)

Source Code

;; Defined in /usr/src/emacs/lisp/calc/calc-units.el.gz
(defun calc-explain-units-rec (expr pow)
  (let ((u (math-check-unit-name expr))
	pos)
    (if (and u (not (math-zerop pow)))
	(let ((name (or (nth 2 u) (symbol-name (car u)))))
	  (if (eq (aref name 0) ?\*)
	      (setq name (substring name 1)))
	  (if (string-match "[^a-zA-Zα-ωΑ-Ω0-9']" name)
	      (if (string-match "^[a-zA-Zα-ωΑ-Ω0-9' ()]*$" name)
		  (while (setq pos (string-match "[ ()]" name))
		    (setq name (concat (substring name 0 pos)
				       (if (eq (aref name pos) 32) "-" "")
				       (substring name (1+ pos)))))
		(setq name (concat "(" name ")"))))
	  (or (eq (nth 1 expr) (car u))
	      (setq name (concat (nth 2 (assq (aref (symbol-name (nth 1 expr))
                                                    0)
					      math-unit-prefixes))
				 (if (and (string-match "[^a-zA-Zα-ωΑ-Ω0-9']" name)
					  (not (memq (car u) '(mHg gf))))
				     (concat "-" name)
				   (downcase name)))))
	  (cond ((or (math-equal-int pow 1)
		     (math-equal-int pow -1)))
		((or (math-equal-int pow 2)
		     (math-equal-int pow -2))
		 (if (equal (nth 4 u) '((m . 1)))
		     (setq name (concat "Square-" name))
		   (setq name (concat name "-squared"))))
		((or (math-equal-int pow 3)
		     (math-equal-int pow -3))
		 (if (equal (nth 4 u) '((m . 1)))
		     (setq name (concat "Cubic-" name))
		   (setq name (concat name "-cubed"))))
		(t
		 (setq name (concat name "^"
				    (math-format-number (math-abs pow))))))
	  (if (math-posp pow)
	      (setq calc-num-units (if calc-num-units
				  (concat calc-num-units " " name)
				name))
	    (setq calc-den-units (if calc-den-units
				(concat calc-den-units " " name)
			      name))))
      (cond ((eq (car-safe expr) '*)
	     (calc-explain-units-rec (nth 1 expr) pow)
	     (calc-explain-units-rec (nth 2 expr) pow))
	    ((eq (car-safe expr) '/)
	     (calc-explain-units-rec (nth 1 expr) pow)
	     (calc-explain-units-rec (nth 2 expr) (- pow)))
	    ((memq (car-safe expr) '(neg + -))
	     (calc-explain-units-rec (nth 1 expr) pow))
	    ((and (eq (car-safe expr) '^)
		  (math-realp (nth 2 expr)))
	     (calc-explain-units-rec (nth 1 expr)
				     (math-mul pow (nth 2 expr))))))))