(math-read-big-expr): Make LaTeX the default TeX mode.

lisp/calc/calc-ext.el

@@ -2947,13 +2947,13 @@ calc-kill calc-kill-region calc-yank))))
        (setq str (concat (substring str 0 (match-beginning 0))
 			 (substring str (match-end 0)))))
   (if (string-match "\\\\[^ \n|]" str)
-      (if (eq calc-language 'tex)
+      (if (eq calc-language 'latex)
 	  (math-read-expr str)
-	(let ((calc-language 'tex)
+	(let ((calc-language 'latex)
 	      (calc-language-option nil)
-	      (math-expr-opers (get 'tex 'math-oper-table))
-	      (math-expr-function-mapping (get 'tex 'math-function-table))
-	      (math-expr-variable-mapping (get 'tex 'math-variable-table)))
+	      (math-expr-opers (get 'latex 'math-oper-table))
+	      (math-expr-function-mapping (get 'latex 'math-function-table))
+	      (math-expr-variable-mapping (get 'latex 'math-variable-table)))
 	  (math-read-expr str)))
     (let ((math-read-big-lines nil)
 	  (pos 0)