diff options
Diffstat (limited to 'lisp/calculator.el')
| -rw-r--r-- | lisp/calculator.el | 59 |
1 files changed, 52 insertions, 7 deletions
diff --git a/lisp/calculator.el b/lisp/calculator.el index 80d68306c28..6f3c2a0e593 100644 --- a/lisp/calculator.el +++ b/lisp/calculator.el @@ -278,7 +278,7 @@ Examples: ("IC" acos (D (acos X)) x 6) ("IT" atan (D (atan X)) x 6) ("Q" sqrt sqrt x 7) - ("^" ^ expt 2 7) + ("^" ^ calculator-expt 2 7) ("!" ! calculator-fact x 7) (";" 1/ (/ 1 X) 1 7) ("_" - - 1 8) @@ -596,7 +596,8 @@ specified, then it is fixed, otherwise it depends on this variable). `+' and `-' can be used as either binary operators or prefix unary operators. Numbers can be entered with exponential notation using `e', except when using a non-decimal radix mode for input (in this case `e' -will be the hexadecimal digit). +will be the hexadecimal digit). If the result of a calculation is too +large (out of range for Emacs), the value of \"inf\" is returned. Here are the editing keys: * `RET' `=' evaluate the current expression @@ -1779,13 +1780,57 @@ To use this, apply a binary operator (evaluate it), then call this." (car calculator-last-opXY) (nth 1 calculator-last-opXY) x)) x)) +(defun calculator-integer-p (x) + "Non-nil if X is equal to an integer." + (condition-case nil + (= x (ftruncate x)) + (error nil))) + +(defun calculator-expt (x y) + "Compute X^Y, dealing with errors appropriately." + (condition-case + nil + (expt x y) + (domain-error 0.0e+NaN) + (range-error + (cond + ((and (< x 1.0) (> x -1.0)) + ;; For small x, the range error comes from large y. + 0.0) + ((and (> x 0.0) (< y 0.0)) + ;; For large positive x and negative y, the range error + ;; comes from large negative y. + 0.0) + ((and (> x 0.0) (> y 0.0)) + ;; For large positive x and positive y, the range error + ;; comes from large y. + 1.0e+INF) + ;; For the rest, x must be large and negative. + ;; The range errors come from large integer y. + ((< y 0.0) + 0.0) + ((oddp (truncate y)) + ;; If y is odd + -1.0e+INF) + (t + ;; + 1.0e+INF))) + (error 0.0e+NaN))) + (defun calculator-fact (x) "Simple factorial of X." - (let ((r (if (<= x 10) 1 1.0))) - (while (> x 0) - (setq r (* r (truncate x))) - (setq x (1- x))) - (+ 0.0 r))) + (if (and (>= x 0) + (calculator-integer-p x)) + (if (= (calculator-expt (/ x 3.0) x) 1.0e+INF) + 1.0e+INF + (let ((r (if (<= x 10) 1 1.0))) + (while (> x 0) + (setq r (* r (truncate x))) + (setq x (1- x))) + (+ 0.0 r))) + (if (= x 1.0e+INF) + x + 0.0e+NaN))) (defun calculator-truncate (n) "Truncate N, return 0 in case of overflow." |