Spline coefficients for data point

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felix.b
felix.b on 15 Oct 2019
Commented: felix.b on 21 Oct 2019
Dear colleagues,
how can I get the spline coefficients for a certain data point?
I know that I can get all the coefficients by using the point-operator (as "pp.coefs"). But how can I get the coefficients for a specific data point (x value). Is there an automatic expression?
Best regards,
Felix

Accepted Answer

Prabhan Purwar
Prabhan Purwar on 18 Oct 2019
Hello,
Spline definesa polynomial among the breakpoints in the curve. To define the coefficient at a particular ‘x value’ there is a need to define an interval among enclosed breakpoints and make use of pp.coefs() as suggested.
Refer to the following link for further information:
  1 Comment
felix.b
felix.b on 21 Oct 2019
Thank you, Prabhan!
That's exactly what I did. If someone encounters the same problem, please see the code below.
C = pp.coefs;
b = (pp.breaks)';
j=0;
for k=1:length(C)
if (((xi >= b(k)) && (xi <= b(k+1))) && (j==0))
j=k;
break
end
end
xS1 = b(j);

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