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Re: Speeding up xy distance calculations using complex numbers [message #84535 is a reply to message #84296]

Mon, 20 May 2013 04:02

Lajos Foldy
Messages: 176
Registered: December 2011

Senior Member

On Saturday, May 18, 2013 11:16:53 AM UTC+2, kagol...@lbl.gov wrote:
>
> distance_squared = z1 * conj(z1)
>

distance_squared is complex, it should be REAL_PART(z1 * conj(z1)), or calculate distance with ABS(z1).(ABS is better, try z1=complex(1e20,1e20))

Also, x^2 can be replaced with x*x:

tmp1=x-p[0]
tmp2=y-p[1]
distance_squared = tmp1*tmp1+tmp2*tmp2

This is the fastest on my machine.

regards,
Lajos

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[Message index]

		Speeding up xy distance calculations using complex numbers By: kagoldberg on Sat, 18 May 2013 02:16
		Re: Speeding up xy distance calculations using complex numbers By: Lajos Foldy on Mon, 20 May 2013 04:02
		Re: Speeding up xy distance calculations using complex numbers By: dg86 on Sun, 19 May 2013 04:32

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