diff options
Diffstat (limited to 'lisp/calc/calc.el')
| -rw-r--r-- | lisp/calc/calc.el | 15 |
1 files changed, 12 insertions, 3 deletions
diff --git a/lisp/calc/calc.el b/lisp/calc/calc.el index ba1c7de9967..04d852e5cb3 100644 --- a/lisp/calc/calc.el +++ b/lisp/calc/calc.el @@ -2773,9 +2773,18 @@ largest Emacs integer.") ;; Coerce integer A to be a bignum. [B S] (defun math-bignum (a) - (if (>= a 0) - (cons 'bigpos (math-bignum-big a)) - (cons 'bigneg (math-bignum-big (- a))))) + (cond + ((>= a 0) + (cons 'bigpos (math-bignum-big a))) + ((= a most-negative-fixnum) + ;; Note: cannot get the negation directly because + ;; (- most-negative-fixnum) is most-negative-fixnum. + ;; + ;; most-negative-fixnum := -most-positive-fixnum - 1 + (math-sub (cons 'bigneg (math-bignum-big most-positive-fixnum)) + 1)) + (t + (cons 'bigneg (math-bignum-big (- a)))))) (defun math-bignum-big (a) ; [L s] (if (= a 0) |