[R] apply

[Steven Yen]

Pardon me!!!

What makes you think this is a homework question? You are not obligated 
to respond if the question is not intelligent enough for you.

I did the following: two ways to calculate a covariance matrix but 
wonder how I might replicate the results with "apply". I am not too 
comfortable with the online do of apply.

> set.seed(122345671) > n<-3 > x<-rnorm(n); x [1] 0.92098449 0.80940115 
0.60374785 > cov1<-outer(x-mean(x),x-mean(x))/(n-1); cov1 [,1] [,2] [,3] 
[1,] 0.0102159207 0.00224105983 -0.0124569805 [2,] 0.0022410598 
0.00049161983 -0.0027326797 [3,] -0.0124569805 -0.00273267965 
0.0151896601 > cov2<-(x-mean(x))%*%t((x-mean(x)))/(n-1); cov2 [,1] [,2] 
[,3] [1,] 0.0102159207 0.00224105983 -0.0124569805 [2,] 0.0022410598 
0.00049161983 -0.0027326797 [3,] -0.0124569805 -0.00273267965 
0.0151896601 >

On 10/4/2024 4:57 PM, Uwe Ligges wrote:
> Homework questions are not answered on this list.
>
> Best,
> Uwe Ligges
>
>
>
> On 04.10.2024 10:32, Steven Yen wrote:
>> The following line calculates standard deviations of a column vector:
>>
>> se<-apply(dd,1,sd)
>>
>> How can I calculate the covariance matrix using apply? Thanks.
>>
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