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Double factorial [wp34s]
02-12-2016, 07:49 AM (This post was last modified: 02-12-2016 07:52 AM by Dieter.)
Post: #3
RE: Double factorial [wp34s]
(02-12-2016 06:27 AM)Paul Dale Wrote:  cos(pi x) can be replaced by (-1)^x which should save a few steps at the start and be faster and more accurate.

Let's not forget CNST, a handy command that IMHO is overlooked too often. CNST 86 is pi/2, and after rearranging the x!! formula to...

\(x!!=2^{\frac{x}{2}}\cdot\left(\frac{\pi}{2}\right)^{\frac{\cos \left ( \pi x \right )-1}{4}}\cdot \left(\frac{x}{2}\right)!\)

...the A program gets quite a bit shorter:

Code:
LBL A
CNST 86
RCL Y
(-1)^x
DEC X
#004
/
y^x
#1/2
RCLx Z
2^x
STOx Y
x<> L
x!
x
RTN

Dieter
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Messages In This Thread
RE: Double factorial [wp34s] - Paul Dale - 02-12-2016, 06:27 AM
RE: Double factorial [wp34s] - Dieter - 02-12-2016 07:49 AM
RE: Double factorial [wp34s] - Dieter - 02-12-2016, 07:54 PM
RE: Double factorial [wp34s] - Paul Dale - 02-13-2016, 12:14 AM
RE: Double factorial [wp34s] - Paul Dale - 02-12-2016, 10:45 AM
RE: Double factorial [wp34s] - Paul Dale - 02-12-2016, 10:33 PM
RE: Double factorial [wp34s] - Paul Dale - 02-13-2016, 10:41 PM
RE: Double factorial [wp34s] - Dieter - 02-15-2016, 07:03 AM
RE: Double factorial [wp34s] - emece67 - 02-13-2016, 12:57 AM
RE: Double factorial [wp34s] - Paul Dale - 02-13-2016, 04:46 AM
RE: Double factorial [wp34s] - Dieter - 02-13-2016, 06:53 AM
RE: Double factorial [wp34s] - Paul Dale - 02-13-2016, 07:05 AM
RE: Double factorial [wp34s] - Dieter - 02-13-2016, 07:00 PM
RE: Double factorial [wp34s] - emece67 - 02-13-2016, 09:15 AM
RE: Double factorial [wp34s] - John Keith - 02-14-2016, 03:24 PM



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