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(calculator-expt): Use more cases to determine the value.

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This commit is contained in:
Jay Belanger 2007-07-04 13:54:30 +00:00
parent aa9f275176
commit b4739e5db1
2 changed files with 27 additions and 8 deletions
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lisp/ChangeLog
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@ -1,3 +1,8 @@
2007-07-04 Jay Belanger <jay.p.belanger@gmail.com>
* calculator.el (calculator-expt): Use more cases to determine
the value.
2007-07-03 Jay Belanger <jay.p.belanger@gmail.com>
* calculator.el (calculator-expt, calculator-integer-p):

30
lisp/calculator.el
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@ -1793,14 +1793,28 @@ To use this, apply a binary operator (evaluate it), then call this."
(expt x y)
(domain-error 0.0e+NaN)
(range-error
(if (> y 0)
(if (and
(< x 0)
(= y (truncate y))
(oddp (truncate y)))
-1.0e+INF
1.0e+INF)
0.0))
(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)