Going backwards in a for loop iteration

I have to make this for loop go backwards when it finishs by the exact simetric path it took till the end of the iterations. It has to be a for loop.

clear all;close all;clc;
A=2;
x=0:0.1:24;
x1=24:-0.1:0;
for lambda=2:0.01:6
    y=A.*cos(2*pi*x/lambda);
    plot(x,y,'linewidth',3);
    drawnow()

end

Answer 1

[Walter Roberson]

for lambda=fliplr(2:0.01:6)