How do you use interp1?

Hello, I am having trouble using the MATLAB function interp1. I want to create a table like the one in the image. My code is provided below. T is a given table you can see in the image. The second image is the one I am getting with the code and I want it to output the one like the third image. I also want the output to be able to take a column array of temperatures and output the calculated values.

function [ T2 ] = interpthermo(T,newT)
Interp_Function=T{sum(T{:,1}<newT),2}+((T{1+sum(T{:,1}<newT),2}-(T{sum(T{:,1}<newT),2}))/(T{1+sum(T{:,1}<newT),1}-T{sum(T{:,1}<newT),1}))*(newT-T{sum(T{:,1}<newT),1});
Temperature=sort([T{:,1};newT]);
new_Column=interp1(Temperature,Interp_Function);
Internal_Energy=sort([T{:,2};new_Column]);
T2=table(Temperature,Internal_Energy);
end

T =

5×2 table

    Temperature    Internal_Energy
    ___________    _______________

     80            2487.3         
    120            2544.7         
    160            2602.7         
    200            2661.4         
    240              2721

>> interpthermo(T,90)

ans =

6×2 table

    Temperature    Internal_Energy
    ___________    _______________

     80            2487.3         
     90            2544.7         
    120            2602.7         
    160            2661.4         
    200              2721         
    240               NaN

>> interpthermo(T,90)

ans =

6×2 table

    Temperature    Internal_Energy
    ___________    _______________

     80            2487.3         
     90            2501.7         
    120            2544.7         
    160            2602.4         
    200            2661.7         
    240              2721