How to generate new vector and replace certain elements?

I have vector X = [3 15 9 12 -1 0 -12 9 6 1].

I want to generate a new vector V which equals X except that the elements of X that are greater than the mean of X are replaced by their difference from the mean of X.

I've tried doing this with

V = X;

V=V(V>mean(V))-mean(V)

But it generates only

10.8 4.8 7.8 4.8 1.8

it doesn't keep the values that are less than the mean.

I'm new to Matlab and have tried approaching it with a loop but I just can't figure it out.

Answer 1

[Guillaume]

Nearly got it:

meanV = mean(V);  %save the mean in a new variable to avoid calculating it more than once
V(V > meanV) = V(V > meanV) - meanV;

[Quick Mart]

Beautiful, thanks!