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Dru Franworth

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Comments and Ratings by Dru		View all 1 - 3 of 3
Updated	File	Comments	Rating
10 Nov 2008	fastsearch Search an element in the array, or the next smaller and greater Author: Valentin Kuklin	I tried the following code in Matlab clear all x=randn(10000,1); tic for i=1:1000000 y=randn; g=find(abs(x-y)==min(abs(x-y))); end toc tic y=sort(x); for i=1:1000000 z=randn; qq=fastsearch(y,z,1); end toc ---------------------------------------------------------------------------------- This is the output: Elapsed time is 423.486252 seconds. Elapsed time is 357.878006 seconds. ----------------------------------------------------------------------------------- An improvement by 15%. Pretty impressive.
10 Nov 2008	fastsearch Search an element in the array, or the next smaller and greater Author: Valentin Kuklin	There is a slight bug in your code. In line 134 , you should have index=fastsearch_indeed(array,von,m1-1,wert,bias); Instead, you have fastsearch(array,von,m1-1,wert,bias); Same thing for line 136. Basically, all you have to do is replace fastsearch in lines 134 and 136 with fastsearch_indeed.
09 Nov 2008	fastsearch Search an element in the array, or the next smaller and greater Author: Valentin Kuklin	I tried the following code and got an error message. As you can see, the number I am searching for is inside the sorted vector but it is generating an error message. ----------------------------------------------------------------------------------- >> x=randn(10000,1); >> y=sort(x); >> z=randn; >> fastsearch(y,z,1) ??? Error using ==> fastsearch Too many input arguments. Error in ==> fastsearch>fastsearch_indeed at 137 index=fastsearch(array,m2+1,bis,wert,bias); Error in ==> fastsearch at 59 index = fastsearch_indeed(array,1,length(array),wert,bias); >> z z = 0.4291 >> min(y) ans = -3.5758 >> max(y) ans = 4.0050 >> find(abs(y-z)==min(abs(y-z))) ans = 6694

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Files Matching Dru's Watch List					1 - 1 of 1
Updated		File	Tags	Downloads (last 30 days)	Comments	Rating
09 Dec 2008		fastsearch Search an element in the array, or the next smaller and greater Author: Valentin Kuklin	search, array, equal, smaller, greater, interpolation	19	8	4.5 4.5 \| 2 ratings

Comments and Ratings Matching Dru's Watch List			1-5 of 8
Date	File	Comment by	Comments	Rating
10 Nov 2008	fastsearch Search an element in the array, or the next smaller and greater	Dru Franworth	I tried the following code in Matlab clear all x=randn(10000,1); tic for i=1:1000000 y=randn; g=find(abs(x-y)==min(abs(x-y))); end toc tic y=sort(x); for i=1:1000000 z=randn; qq=fastsearch(y,z,1); end toc ---------------------------------------------------------------------------------- This is the output: Elapsed time is 423.486252 seconds. Elapsed time is 357.878006 seconds. ----------------------------------------------------------------------------------- An improvement by 15%. Pretty impressive.	Comment only
10 Nov 2008	fastsearch Search an element in the array, or the next smaller and greater	Dru Franworth	There is a slight bug in your code. In line 134 , you should have index=fastsearch_indeed(array,von,m1-1,wert,bias); Instead, you have fastsearch(array,von,m1-1,wert,bias); Same thing for line 136. Basically, all you have to do is replace fastsearch in lines 134 and 136 with fastsearch_indeed.	Comment only
09 Nov 2008	fastsearch Search an element in the array, or the next smaller and greater	Dru Franworth	I tried the following code and got an error message. As you can see, the number I am searching for is inside the sorted vector but it is generating an error message. ----------------------------------------------------------------------------------- >> x=randn(10000,1); >> y=sort(x); >> z=randn; >> fastsearch(y,z,1) ??? Error using ==> fastsearch Too many input arguments. Error in ==> fastsearch>fastsearch_indeed at 137 index=fastsearch(array,m2+1,bis,wert,bias); Error in ==> fastsearch at 59 index = fastsearch_indeed(array,1,length(array),wert,bias); >> z z = 0.4291 >> min(y) ans = -3.5758 >> max(y) ans = 4.0050 >> find(abs(y-z)==min(abs(y-z))) ans = 6694	Comment only
06 May 2008	fastsearch Search an element in the array, or the next smaller and greater	Valentin Kuklin	Hi Alexander, thanks for your notes. I think there is no bug. This code with "Check if wert is inside of array." is used only for the first run, for example if you have array=1:1:100 and you search -5 or 105. For the further runs it does not play any role, the searched number will be anyway within [von, bis]. Actually it can not be infinite recursion because every "if" ends with "return" but not with the new call of function. But anyway I am happy that someone uses my function and tries to find bugs :) Thanks again :) Valentin Kuklin	Comment only
05 May 2008	fastsearch Search an element in the array, or the next smaller and greater	Alexander Chemeris	It's good that such a useful algorithm in finally implemented in Matlab :) But this implementation have a bug. "Check if wert is inside of array." should looks like: if wert<array(von) if bias==1 index=von; return; else index=-1; return; end end if wert>array(bis) if bias == -1 index = bis; return; else index = -1; return; end end That is "von" and "bis" are used instead of "1" and "end". Without this fix algorthm may enter infinite recursion in certain cases.	4

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