# [R] Random projection

Jeff Newmiller jdnewmil @ending from dcn@d@vi@@c@@u@
Wed Dec 5 00:32:36 CET 2018

```Your multiplication description sounds more like matrix multiplication than scalar multiplication. R supports matrix multiplication with the %*% operator.

I didn't follow the rest of your description... are you doing a homework assignment? There is a no homework policy on this list...

On December 4, 2018 2:06:43 PM PST, rosie fleming <rosiefleming using hotmail.co.uk> wrote:
>Hello I was wondering if anyone could help. I am using R to perform
>random projection on Gaussians.
>I need to take k Gaussian random vectors U1,...,Uk in R(reals)
>Then for any vector v in d dimensions, perform the random projection:
>f(v) = v.U1, v.U2, ..., v.Uk which reduces v from d dimensions to k
>dimensions
>So i need v1,...vn so n vectors
>
>and then the basic idea is that the relative orders will be preserved
>between the vectors v after projection ie the nearet neighbours for
>each vectors will be the same before projection (v1,v2,...,vn) and
>after projection f(v1),...f(vk)
>
>I'm struggling to produce this in R. I've managed to make a matrix for
>U and V
>However I now need to use the scalar product to perform the projection,
>taking each row of v (vi) and multiplying it with every column of the U
>matrix. I need to perform this for n vectors and have a matrix as the
>outcome.
>
>This would then allow me to find the distances between each f(vi)!
>
>Any help would be greatly appreciated, thankyou!
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