Re: cmplx(0.,-x) or -j*x
- From: robin <robin_v@xxxxxxxxxxxxxxxxxx>
- Date: Thu, 26 May 2005 12:29:08 GMT
gh14tq5@xxxxxxxxx writes: > Hi,
>
> Is there any speed advantage of using
>
> z = cmplx(0,-x) over z = -j*x (or vice-versa)
>
> where x is real and possible an array and j=sqrt(-1). Would this be
> something that is compiler dependent?
Isn't J going to be complex?
And therefore j*x is going to involve scalar multiplication
twice (j*0 and j*x).
This will be somewhat longer than using cmplx,
which just does two moves (0 into the real part and
-x to the unreal part).
> Thanks,
> John
.
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