필터 지우기
필터 지우기

Fit a spline function to a set of data points

조회 수: 52 (최근 30일)
Deepa Maheshvare
Deepa Maheshvare 2022년 7월 3일
댓글: Deepa Maheshvare 2022년 7월 4일
Hi All,
I have a set of coordinate points
x= [0,4,6,10,15,20]
y = [18,17.5,13,12,8,10]
I want to fit a spline function.
Could someone please suggest the the curve fit function that can be used?
  댓글 수: 7
Deepa Maheshvare
Deepa Maheshvare 2022년 7월 3일
x = [0,4,6,10,15,20]
y = [18,17.5,13,12,8,10]
vq = interp1(x,y,'linear')
returns NaN
Deepa Maheshvare
Deepa Maheshvare 2022년 7월 3일
I tried
x = [0,4,6,10,15,20]
v = [18,17.5,13,12,8,10]
vq = interp1(x,v, 'linear', 'pp')
xq = x
figure
vq1 = interp1(x,v,xq);
plot(x,v,'o',xq,vq1,':.');
title('(Default) Linear Interpolation');
returns
vq =
struct with fields:
form: 'pp'
breaks: [0 4 6 10 15 20]
coefs: [5×2 double]
pieces: 5
order: 2
dim: 1
orient: 'first'
Here I am not sure why the order (which I infer as the polynomial degree) is 2 for linear interpolation. Could you please explain this a bit?

댓글을 달려면 로그인하십시오.

채택된 답변

Sam Chak
Sam Chak 2022년 7월 3일
Thought you want the 'spline'? Is there a reason to use the 'linear' method?
x = [0, 4, 6, 10, 15, 20];
y = [18, 17.5, 13, 12, 8, 10];
xq = 0:0.01:20;
subplot(2,1,1)
yq1 = interp1(x, y, xq, 'linear');
plot(x, y, 'o', xq, yq1, '--');
ylim([5 22]), grid on, title('Linear Interpolation');
subplot(2,1,2)
yq2 = interp1(x, y, xq, 'spline');
plot(x, y, 'o', xq, yq2, '--');
ylim([5 22]), grid on, title('Spline Interpolation');
  댓글 수: 3
Torsten
Torsten 2022년 7월 3일
Seems that order = 2 means that two coefficients are needed to describe the (linear) spline function on each subinterval and is set to 1 + degree of the interpolating polynomial. A bit confusing in my opinion.
Deepa Maheshvare
Deepa Maheshvare 2022년 7월 4일
Thanks a lot for the clarification.

댓글을 달려면 로그인하십시오.

추가 답변 (1개)

Simon Chan
Simon Chan 2022년 7월 3일
Use function spline

카테고리

Help CenterFile Exchange에서 Interpolation에 대해 자세히 알아보기

제품


릴리스

R2021a

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by