# Solving quadratic equations with covariance term

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## Solving quadratic equations with covariance term

 Hi, I would like to solve the following equation with R: Cov(A,x)=0. A is a given matrix, x is the an unknown vector. Is there any nice solution for this? Thank you for your help. Best wishes, Luba Stein         [[alternative HTML version deleted]] ______________________________________________ [hidden email] mailing list https://stat.ethz.ch/mailman/listinfo/r-helpPLEASE do read the posting guide http://www.R-project.org/posting-guide.htmland provide commented, minimal, self-contained, reproducible code.
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## Re: Solving quadratic equations with covariance term

 On 7/07/2009, at 2:15 AM, Stein, Luba (AIM SE) wrote: > Hi, > > I would like to solve the following equation with R: Cov(A,x)=0. > A is a given matrix, x is the an unknown vector. > > Is there any nice solution for this? What on earth do you mean by ``Cov(A,x)''?  This makes no sense at all.         cheers,                 Rolf Turner ###################################################################### Attention:\ This e-mail message is privileged and confid...{{dropped:9}} ______________________________________________ [hidden email] mailing list https://stat.ethz.ch/mailman/listinfo/r-helpPLEASE do read the posting guide http://www.R-project.org/posting-guide.htmland provide commented, minimal, self-contained, reproducible code.
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## Re: Solving quadratic equations with covariance term

 Hi, more precisely I consider a matrix with three column vectors a_i (i=1,2,3), i.e. A=(a_1,a_2,a_3). On the other hand x should take vectors as values, i.e. x=v_j, while j goes also from 1 till 3. Now I just want to calculate the equation Cov(a_i,x_j) = 0, where Cov(a_i,x_j) is the covariance matrix. A is a given value and x is the variable I am looking for. In my opinion this is an quadratic equation and makes sense. Best wishes, Luba -----Urspr?ngliche Nachricht----- Von: Rolf Turner [mailto:[hidden email]] Gesendet: Montag, 6. Juli 2009 23:16 An: Stein, Luba (AIM SE) Cc: [hidden email] Betreff: Re: [R] Solving quadratic equations with covariance term On 7/07/2009, at 2:15 AM, Stein, Luba (AIM SE) wrote: > Hi, > > I would like to solve the following equation with R: Cov(A,x)=0. > A is a given matrix, x is the an unknown vector. > > Is there any nice solution for this? What on earth do you mean by ``Cov(A,x)''?  This makes no sense at all.         cheers,                 Rolf Turner ###################################################################### Attention: This e-mail message is privileged and confidential. If you are not the intended recipient please delete the message and notify the sender. Any views or opinions presented are solely those of the author. This e-mail has been scanned and cleared by MailMarshal www.marshalsoftware.com ###################################################################### ______________________________________________ [hidden email] mailing list https://stat.ethz.ch/mailman/listinfo/r-helpPLEASE do read the posting guide http://www.R-project.org/posting-guide.htmland provide commented, minimal, self-contained, reproducible code.