Ich habe Dein File entsprechend modifiziert:
%% HOW DO I DO THAT IN MATLAB SERIES?
% In this series, I am answering questions that students have asked
% me about MATLAB. Most of the questions relate to a mathematical
% procedure.
%% TOPIC
% How do I do spline interpolation?
%% SUMMARY
% Language : Matlab 2008a;
% Authors : Autar Kaw;
% Mfile available at
% http://numericalmethods.eng.usf.edu/blog/interpolate_spline.m;
% Last Revised : June 20, 2009;
% Abstract: This program shows you how to do spline interpolation?
% .
clc
clear all
clf
%% INTRODUCTION
disp('ABSTRACT')
disp(' This program shows you how to do spline interpolation?')
disp(' ')
disp('AUTHOR')
disp(' Autar K Kaw of http://autarkaw.wordpress.com')
disp(' ')
disp('MFILE SOURCE')
disp(' http://numericalmethods.eng.usf.edu/blog/interpolation_spline.m')
disp(' ')
disp('LAST REVISED')
disp(' June 20, 2009')
disp(' ')
%% INPUTS
% y vs x data to interpolate
% x data
x=[-1 -0.75 -0.5 -0.25 0.25 0.50 0.75 1];
% ydata
y=[-0.5 -0.5 -0.5 -0.5 0.5 0.5 0.5 0.5];
% Where do you want to interpolate at
xin=x;
%% DISPLAYING INPUTS
disp('INPUTS')
disp('The x data')
x
disp('The y data')
y
disp('The x values where you want to find the interpolated values')
xin
disp(' ')
%% THE CODE
% Fitting to spline - it is cubic splines
yin=spline(x,y,xin);
% This is only for plotting the spline interpolants
% Find the number of data points
n=length(x);
xplot=x(1):(x(n)-x(1))/10000:x(n);
yplot=spline(x,y,xplot);
x'
y'
f = fit(x',y','smoothingspline');
%% DISPLAYING OUTPUTS
disp(' ')
disp('OUTPUTS')
disp('x values at which function is to be interpolated')
xin
disp('y values at the xin values')
yin
xlabel('x');
ylabel('y');
title('y vs x ');
subplot(2,1,1);
plot(x,y,'o','MarkerSize',10,'MarkerEdgeColor','b','MarkerFaceColor','b')
hold on
plot(xin,yin,'o','MarkerSize',10,'MarkerEdgeColor','r','MarkerFaceColor','r')
hold on
plot(xplot,yplot,'LineWidth',2)
legend('Points given','Points found','Spline Curve','Location','East')
hold off
disp(' ')
subplot(2,1,2);
plot(f,x',y');
