如何在Matlab中读取表，找到与x对应的y值

Question

I want to use the y value corresponding to the given x value from the table (my current table has 1000 values with 10-4 decimal points so I use :

load question_table.mat
eta_p = %assign a value 
F12_p=find( (eta <eta_p+0.01) & (eta > eta_p-0.01), 1, 'first' )

what is missing ?

Here is how I have created the table, run this program.

i = 1;
etaspan = -500:0.001:500;
y = zeros(length(etaspan),1);
f = @(x,eta) (x.^(1/2))./(1+exp(x-eta));

for eta = etaspan
   g = @(x) f(x,eta);
   y(i) = integral(g,0,500);
   i = i + 1;
end

---

f=y 
eta=etaspan 
save question_table.mat eta f

Answer 1

Just have MATLAB do the interpolation for you:

y_p = interp1(eta, y, eta_p);

interp1 uses linear interpolation by default, but can instead use higher order interpolation methods. Even with linear, your table seems much denser than necessary.