How can I add query points between two adjacent points of sampled data and perform interpolation?

I have a representative subset of sample points as shown above, and intend to define the query points to be a finer sampling over the range of x, for example, to add 10 query points (evenly) in interval of any two adjacent points in column A (x), then interpolate using the "linear" or "spline" method.

[Mathieu NOE]

hello

it would be more efficient to share your data and code , so someone can work on your problem

Answer 1

[Voss]

Calculate the query points exactly as I showed in my answer to your other question

https://www.mathworks.com/matlabcentral/answers/2086288-how-can-i-add-query-points-between-two-adjacent-points-of-sampled-data#answer_1415688

x = [-21.0598;-20.8076;-20.553;-20.307;-20.0533;-19.7929;-19.5517;-19.3;-19.0503;-18.777];
y = [-9.1948;-9.2299;-9.2583;-9.2909;-9.3189;-9.3527;-9.3784;-9.4144;-9.441;-9.4736];

n = 10; % number of points to insert in each interval
N = numel(x);
q = linspace(1,N,(n+1)*(N-1)+1);
Xq = interp1(1:N,x,q).'; % query points

Then interpolate:

% interpolated results:
Yq_linear = interp1(x,y,Xq);
Yq_spline = interp1(x,y,Xq,'spline');

Visualization of the results:

tiledlayout(2,1)
nexttile()
plot(x,y,'o')
hold on
plot(Xq,Yq_linear,'.-')
legend({'Data','Linear'})

nexttile()
plot(x,y,'o')
hold on
plot(Xq,Yq_spline,'.-')
legend({'Data','Spline'})