Y 1=a+blogX 1
Y2=a+blogX2
...
Yn=a+blogXn
This is an overdetermined equation with two unknown elements A and B (the number of equations is much larger than the number of unknown elements), which can be solved by least square method, even if
(Y 1-a-blogX 1)^2+...+(Yn-a-blogXn)^2=min
Minimum value, determine a and b, and finally solve an ordinary equation.