x=[1 2 3 4]
y=[5 7 9 9]
this code worked well.
Your question is littel bit concusing. It is not clear.
Do you mean that if we apply log10(x) we should get y ??
the valurswhich are stored in y are not the log10(x) values.
observe that y is having two 9's. you cant get the same value for both 3 and 4.
I think this must clear your doubt.if not please specify the question more clearely.
give up thumb if this answer works. Thank you.