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Code Issues Releases Activity

(calculator-expt, calculator-integer-p): New functions.

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(calculator-fact): Check to see if the factorial will be too large
before computing it.
(calculator-initial-operators): Use `calculator-expt' to compute "^".
(calculator-mode): Mention that results which are too large will return inf.
This commit is contained in:
Jay Belanger 2007-07-04 04:20:35 +00:00
parent b71f9bdb2d
commit f50347a91b
2 changed files with 49 additions and 7 deletions
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11
lisp/ChangeLog
View File

@ -1,3 +1,14 @@
2007-07-03 Jay Belanger <jay.p.belanger@gmail.com>
* calculator.el (calculator-expt, calculator-integer-p):
New functions.
(calculator-fact): Check to see if the factorial will be too
large before computing it.
(calculator-initial-operators): Use `calculator-expt' to
compute "^".
(calculator-mode): Mention that results which are too large
will return inf.
2007-07-03 David Kastrup <dak@gnu.org>
* shell.el: On request of the authors, remove their addresses for

45
lisp/calculator.el
View File

@ -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 +1780,43 @@ 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
(if (> y 0)
(if (and
(< x 0)
(= y (truncate y))
(oddp (truncate y)))
-1.0e+INF
1.0e+INF)
0.0))
(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."