make my curve smooth

Hello,

Due to low sample rate my curve is not coming smooth, so I want to make it smooth

This is the code I am writting:

filename = 'All Data_10mm.xlsx';

%

sheet = '10 mm_1hz_0V_Test1'; % add sheet number

xlRange = 'B80:B101'; % X range

ylRange = 'E80:E101'; % Y range

[Disp, text, raw]= xlsread(filename,sheet,xlRange);

[force, text, raw]= xlsread(filename,sheet,ylRange);

plot(Disp,force,'-r')

hold all

grid on

grid minor

[Rik]

Have you looked at the spline function?

[Adam Danz]

I was just about to suggest spline, too. Also see

https://www.mathworks.com/help/curvefit/examples/constructing-spline-curves-in-2d-and-3d.html

Answer 1

[Star Strider]

This is as close as I can get to what you want:

filename = 'All Data_10mm.xlsx';
sheet = '10 mm_1hz_0V_Test1';      % add sheet number 
xlRange = 'B80:B101';       % X range
ylRange = 'E80:E101';      % Y range
[Disp, text, raw]= xlsread(filename,sheet,xlRange);
[force, text, raw]= xlsread(filename,sheet,ylRange);
plot(Disp,force,'-r')
hold all
grid on
grid minor

[minx,idx1] = mink(Disp,3);
[maxx,idx2] = maxk(Disp,2);
idxv = sort([idx1; idx2]);

for k = 1:numel(idxv)-1
    xi = [idxv(k), idxv(k+1)];
    Dispv(k,:) = linspace(Disp(xi(1)), Disp(xi(2)), 150);
%     qx = Disp(xi(1):xi(2))
%     qy = force(xi(1):xi(2))
    forcev(k,:) = interp1(Disp(xi(1):xi(2)), force(xi(1):xi(2)), Dispv(k,:), 'pchip');
end

figure
plot(Dispv', forcev')
grid
title('‘pchip’ Interpolation')

producing:

Feel free to experimant with it.