Fixing the x ticks for a plot

I have a variable named 'a' of the size 20x40 double and I am trying to plot it. At first I ploted it, without specifying the tick values and Matlab is generating the auto ticks for me. Now, I want to take those ticks and multiply it with a constant and update the previous ticks with the new ones.

I approached it using two ways but both the codes have some flaw to them.

1) In this code I am trying to multiply a constant with the old ticks and then updating it with the new ticks but the xtick values don't make sense. They appear right in the workspace but they dont show up correctly on the plot.

    xticks = get(gca,'xtick');     % reads old x ticks
    constant  = 0.25; 
    new_Xticklabels = arrayfun(@(x) sprintf('%.0f', constant * x), xticks, 'un', 0);
    set(gca,'xticklabel',new_Xticklabels);
    yticks = get(gca,'ytick');     %reads old y ticks
    new_Yticklabel=arrayfun(@(y) sprintf('%.0f', constant * y), yticks, 'un', 0);
    set(gca,'yticklabel',new_Yticklabel);
   

2)In the second code I tried to specify the x and the y ticks and used the labels to show the value but in doing that the graph shows up with empty spots.

    xticks([12 20 32 40]);
    xticklabels({'3','5','8','10'});
    yticks([8 16 24 32 40 48 56 64]);
    yticklabels({'2','4','6','8','10','12','14','16'});

Any help would be appreciated.

Thank you.

[Walter Roberson]

Which MATLAB release are you using?

[Raza]

I am using the 2018b release.

[Walter Roberson]

Both versions appear to work for me.

[Agnish Dutta]

The first version seems to be working fine.

The second one may be giving problems because the of values you are specifying as input to the "xticks" function may be out of the range.