Kahan summation algorithm

12192014, 09:12 PM
(This post was last modified: 12192014 09:48 PM by Thomas Klemm.)
Post: #1




Kahan summation algorithm
For details please consult Wikipedia.
Program for the HP42S: Code: 00 { 19Byte Prgm } Worked example: \(10^{10}+\pi+e\) CLST E10 ENTER 0 PI XEQ "KAHAN" 1 E↑X R/S y: 10,000,000,005.9 x: 0.04012551795 This is the correctly rounded result. The classic addition is not the same: E10 PI + 1 E↑X + y: 0 x: 10,000,000,005.8 Cheers Thomas 

12202014, 09:47 AM
Post: #2




RE: Kahan summation algorithm
Thank you. Never seen this before.


12212014, 08:52 AM
Post: #3




RE: Kahan summation algorithm
What I have never seen mentioned is the fact that this algorithm is meant for binary floating point. Try adding x=y= 1e122
You'll get s := 2e12 c := 2, while it should be 4 BTW my version reads: Code: *LBL "K+" same size. Werner 

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