;; Additional mactex utilities.
;; All functions are based on code by Richard J. Fateman, copyright 1987.
;; Fateman's code was ported to Common Lisp by William Schelter.

;; If you want LaTeX style quotients, first load mactex and second
;; define tex-mquotient as follows

(defun tex-mquotient (x l r)
  (if (or (null (cddr x)) (cdddr x)) (wna-err (caar x)))
  (setq l (tex (cadr x) (append l '("\\frac{")) nil 'mparen 'mparen)
	r (tex (caddr x) (list "}{") (append '("}") r) 'mparen 'mparen))
  (append l r))

;; (defprop mtimes ("\\,") texsym)
;; adds a thin space.
;; The following tells TeX to use whatever it thinks best.
;; (defprop mtimes (" ") texsym)

;; To use amsmath style matrices, define tex-matrix as
;; (to TeX the code, you'll need to \usepackage{amsmath})

(defun tex-matrix (x l r) ;; matrix looks like ((mmatrix)((mlist) a b) ...)
  (append l `("\\begin{pmatrix}")
	 (mapcan #'(lambda(y)
			  (tex-list (cdr y) nil (list " \\\\ ") " & "))
		 (cdr x))
	 '("\\end{pmatrix}") r))

;; Here is a version of tex-limit that doesn't ignore the direction of
;; the limit; it uses down and up arrows to indicate the direction.

(defun tex-limit(x l r)
  (let* ((s1 (tex (cadr x) nil nil 'mparen rop))
	 (arrow
	  (cond ((eq (nth 4 x) '$minus)
		 " \\,  \\downarrow  \\,")
		((eq (nth 4 x) '$plus)
		 " \\, \\uparrow \\, " )
		(t
		  " \\rightarrow ")))
	 (subfun  (subst arrow '=
			 (tex `((mequal simp) ,(caddr x),(cadddr x))
			      nil nil 'mparen 'mparen))))
    (append l `("\\lim_{" ,@subfun "}{" ,@s1 "}") r)))