Re: [eigen] Complex number divided by real |

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*To*: eigen@xxxxxxxxxxxxxxxxxxx*Subject*: Re: [eigen] Complex number divided by real*From*: Gael Guennebaud <gael.guennebaud@xxxxxxxxx>*Date*: Wed, 21 Jul 2010 23:52:11 +0200*Dkim-signature*: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:mime-version:received:in-reply-to :references:from:date:message-id:subject:to:content-type :content-transfer-encoding; bh=BlK46xNHoCINzPDS9q29TlsdhJqyXLKb6zKrNIlLeb4=; b=KU4KnX4XXdQAgrX97pHSrAC5Y0r09cLUTEXklg09qiG/lqbDwd5Kiybcrpa83kozZu uvQIv0a+JFgzePMq5Hd9DnbEWXDgfnczQmtoXpZk15YZ1RgmHc64Nca4ncWq84d1A/FS CVNaPHuMWEQiA8fR5sKmqrfX6fj9/79niXCr4=*Domainkey-signature*: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :content-type:content-transfer-encoding; b=MaOUTeXP53PC9+9uzXJdHoNPzGtPv/jRMXLMKUxCxxzBafzb1WUxbSX7ER1+7mhRiG GfEeKCDjiy3FHS2FrG/EXJe+gAu4UlYQw9YVJmAWEpkwpaOud+3TY2wewasavakBuN3q aZmsWyQKMTnEufJwTgwAm1ZWFARy7aA09XoVY=

for the record, let me just paste what I've replied on IRC: [19:34] <ggael> artz: currently yes you have to do the cast but for beta2 this will work just fine doing a complex/real division. [19:34] <ggael> hm, actually the following should work too: [19:35] <ggael> (complex array) * (real array).inverse() [19:35] <ggael> the trick is that operator* already works for mixed complex*real coefficient-wise product gael. On Wed, Jul 21, 2010 at 7:33 PM, Carlos Becker <carlosbecker@xxxxxxxxx> wrote: > Hi everyone, > (first, I am using the dev branch) > I am trying to do something like (a.array() * b.array().conjugate()) / ( > a.array().abs() * b.array().abs() ), where a and b are two VectorXcf. The > problem is that (according to what I see) a.array().abs() returns a real > vector rather than a complex one. So I can fix that by casting to > std::complex<float> but that would incurr in a performance loss right? > I could normalize each value and then multiply, but I would have two > divisions, and I don't even know if this 'element' normalization is possible > with Eigen in its current state. > I know there are changes being done to the complex part so I guess this is a > good point to ask about this. Maybe supporting complex divided by real would > be good for certain operations. I could also save it to a complex and then > take the result as a real vector that is twice the size of the complex ones > but I guess that it would be a performance loss since there would be many > unnecessary accesses to memory. > Thanks, > Carlos

**References**:**[eigen] Complex number divided by real***From:*Carlos Becker

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