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Re: [Q]: ID analog to FORTRAN "sign" function [message #21989 is a reply to message #21932]

Thu, 12 October 2000 13:50

Mark Hadfield
Messages: 783
Registered: May 1995

Senior Member

"Dick Jackson" <dick@d-jackson.com> wrote in message
news:8MkF5.12$953.172@read1...
> Do I dare offer one more? Subscript lookups seem faster than arithmetic
> operations, making this one faster, more compact and no less cryptic! :-)
>
> Return, Abs(a) * ([-1, 1])[b GE 0]

Good one!

> A bit faster still, if you know the expected type of a and b, to avoid an
> extra type conversion:
>
> Return, Abs(a) * ([-1.0, 1.0])[b GE 0]

I think that's a little *too* clever. I just tried multiplying a float array
with 10^7 elements by 1 and then by 1.0. Time taken = 0.52 seconds in both
cases.

---
Mark Hadfield
m.hadfield@niwa.cri.nz http://katipo.niwa.cri.nz/~hadfield/
National Institute for Water and Atmospheric Research
PO Box 14-901, Wellington, New Zealand

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[Message index]

		[Q]: ID analog to FORTRAN "sign" function By: Rostyslav Pavlichenko on Fri, 06 October 2000 22:34
		Re: [Q]: ID analog to FORTRAN "sign" function By: Mark Hadfield on Thu, 12 October 2000 13:50
		Re: [Q]: ID analog to FORTRAN "sign" function By: Phillip David on Thu, 12 October 2000 00:00
		Re: [Q]: ID analog to FORTRAN "sign" function By: Dick Jackson on Thu, 12 October 2000 00:00
		Re: [Q]: ID analog to FORTRAN "sign" function By: Mark Hadfield on Mon, 09 October 2000 14:45
		Re: [Q]: ID analog to FORTRAN "sign" function By: Dick Jackson on Fri, 13 October 2000 00:00

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