how to use spline for a fig. file?

Can I use spline to smooth the plot in attached file?

Answer 1

[Star Strider]

Try this:

I = openfig('fft scma 25.fig');
Ax = gca;
lgnd = Ax.Legend;
Lines = findobj(Ax,'Type','line');
N = 5;                                                              % Interpolation Points Length Multiplication
for k = 1:numel(Lines)
    X(k,:) = Lines(k).XData;
    Y(k,:) = Lines(k).YData;
    xq(k,:) = linspace(min(X(k,:)),max(X(k,:)), numel(X(k,:))*N);   % Interpolation Points Vector
    ys(k,:) = spline(X(k,:),Y(k,:),xq(k,:));                        % Spline Fit To Data
end

figure
semilogy(xq', ys')
grid
legend(Ax.Legend.String)
xlabel(Ax.XLabel.String)
ylabel(Ax.YLabel.String)

Change ‘N’ to get the result you want.

This is essentially the same as my previous code, this time doing a spline interpolation.

EDIT —

Corrected typographical error. Code unchanged.

Answer 2

[Walter Roberson]

Ninterp = 10;
Nplot = 100;
fig = openfig('fft scma 25.fig');
Lines6to1 = findobj(fig, 'type', 'line');
for idx = 1 : length(Lines6to1)
    h = Lines6to1(idx);
    xd = get(h, 'XData');
    yd = get(h, 'YData');
    x = linspace(min(xd), max(xd), Ninterp);
    y = interp1(xd, yd, x, 'spline');
    xx = linspace(min(xd), max(xd), Nplot);
    yy = spline(x, y, xx);
    set(h, 'XData', xx, 'YData', yy);
end

[Sajid Sarwar]

thank u Walter Roberson and Star Strider