MATLAB: How to write a code for varying step size

variable step size

Hi! I'm working on boundary layer theory.I've written a code for solving block tri-diagonal matrix.One of the variable i've taken with variable step size to get a good accuracy.Have used if loop .While executing it takes the first if condition and executes for the whole interval as my initialization is 0.As my incremental value is the varying parameter how to bring it?
x_bar=0;
        if x_bar<=0.5 
          delx_bar=0.01;
        elseif x_bar >=0.5 && x_bar <=1.25
            delx_bar=0.005;
         else
            delx_bar=0.0001;
        end
%%Intial profiles start
x_bar=0:delx_bar:1.25;
n_xbar=length(x_bar);
As I've used x_bar and length of x_bar in the code for calculation of values i need to define it. What changes do I have to make so that my x_bar values are generated first and then the successive delx_bar are taken for calculation of values.

Best Answer

Xb = [0, .5, 1.25, 2];
dx = [.01, .005, .0001];
x_bar = cumsum([Xb(1), repelem(dx,diff(Xb)./dx)]);
>> x_bar_j = 1.589
delx_bar_j = dx(discretize(x_bar_j,Xb))
x_bar_j =
        1.589
delx_bar_j =
       0.0001
>>
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