Reflecting impulse response with respect to y-axis

Greetings, I have a discrete-time signal at the +x-axis. I'm having a problem to reflect the signal with respect to the y-axis so that my signal is located at the -x-axis.

Example, I have a impulse response of Hn=[4 2 1 0.5] which means h[0]=4, h[1]=2, h[3]=1 and h[4]=0.5. So i would like to reflect the impulse response with respect to the y-axis so that the response will be h[-3]=0.5, h[-2]=1, h[-1]=2 and h[0]=4.

Answer 1

[Rick Rosson]

n = -3:0;
h = fliplr(Hn);
stem(n,h);

[Jimmy]

It worked. Thank you so much

[Jimmy]

my second question is that how to apply time reversal convolution after reflecting the new impulse response?

[Rick Rosson]

Please post a new question so that more people will see it.