Quadratic Spline Interpolation Code
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What is the MATLAB code for quadratic splines? As linear uses interp1 linear and cubic splines uses interp1 spline. What is the corresponding interp1 coding for quadratic splines?
1 个评论
darova
2020-4-28
Matlab has no quadratic spline
Try FILEEXCHANGE
回答（2 个）
Ameer Hamza
2020-4-28
编辑：Ameer Hamza
2020-4-28
You can write your own quadratic spline function
function yq = quadSpline(x, y, xq)
X = [x(:).^2 x(:) ones(size(x(:)))];
coff = X\y(:);
yq = [xq(:).^2 xq(:) ones(size(xq(:)))]*coff;
end
Example
x = 1:10;
y = x.^2 + 5 + rand(size(x))*10;
xq = linspace(0,10);
yq = quadSpline(x, y, xq);
plot(x, y, 'r+', 'MarkerSize', 10, 'LineWidth', 2);
hold on
plot(xq, yq, 'b-');
4 个评论
Enes Senel
2020-12-14
this is not quadratic spline
Rik
2020-12-14
Can you show what is wrong with his function? Can you provide a suggestion to fix it?
Enes Senel
2020-12-14
splines should pass from data points. This seems like polynomial regression
John D'Errico
2020-12-14
编辑：John D'Errico
2020-12-14
The comments are correct. This is NOT a quadratic spline tool. All that is given in this answer is a quadratic polynomial regression. That is not a spline. The comment about a spline passing through the data points is not always correct though. An INTERPOLATING spline passes through the data points. However, regression or smoothing splines need not do so. But as said, this still is not a spline, in the sense that a spline is a piecewise function.
Bruno Luong
2020-12-14
0 个投票
My toolbox provide any order (1D) spline, including quadratic
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2020-4-28
2020-12-14
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