MATLAB Help - Quadratic Splines

[@harshdhiman3236]

Who else felt extremely satisfied when he plotted the quadratic spline in the end?
Thanks so much for this. This was incredibly helpful.

[@lenewang843]

Thanks for the detailed explainations! Very helpful! Head to cubic splines now!

[@CarlosMontalvo251]

ruclips.net/video/gfSKOfHRooQ/видео.html

[@v54474]

Great video. Would you please share your codes for quadratic spline?

[@CarlosMontalvo251]

clear
clc
close all
X = (-10:10)';
Y = sin(5*X);% + rand(length(X),1);
fig = figure();
set(fig,'color','white')
set(gca,'FontSize',18)
p0 = plot(X,Y,'b*','MarkerSize',10);
xlabel('X')
ylabel('Y')
grid on
hold on
%%%Linear Splines
for idx = 1:length(X)-1
m = (Y(idx+1)-Y(idx) )/(X(idx+1)-X(idx));
xspline = linspace(X(idx),X(idx+1),10);
yspline = m*(xspline-X(idx)) + Y(idx);
p1 = plot(xspline,yspline,'g-','LineWidth',2);
end
%%%Quadratic Splines
N = length(X);
n = N-1;
%%%%Create H0 = [2*(n-1) x 3*n]
H0 = zeros(2*n-2,3*n);
K0 = zeros(2*n-2,1);
for idx = 1:(n-1)
col = idx;
row = 2*(idx-1)+1;
H0(row,col) = X(idx+1)^2;
H0(row+1,col+1) = X(idx+1)^2;
H0(row,n+col) = X(idx+1);
H0(row+1,n+col+1) = X(idx+1);
H0(row,2*n+col) = 1;
H0(row+1,2*n+col+1) = 1;
K0(row) = Y(idx+1);
K0(row+1) = Y(idx+1);
end
%%%Create H1 = [n-1 x 3*n];
H1 = zeros(n-1,3*n);
for idx = 1:n-1
H1(idx,idx) = 2*X(idx+1);
H1(idx,idx+1) = -2*X(idx+1);
H1(idx,n+idx) = 1;
H1(idx,n+idx+1) = -1;
end
%%%Create HE
HE = zeros(2,3*n);
HE(1,1) = X(1)^2;
HE(1,n+1) = X(1);
HE(1,2*n+1) = 1;
HE(2,n) = X(end)^2;
HE(2,2*n) = X(end);
HE(2,end) = 1;
%%%Compute H
H = [H0;H1;HE];
[r,c] = size(H);
%%%Compute K
K = zeros(r,1);
K(1:(2*(n-1))) = K0;
K(end-1) = Y(1);
K(end) = Y(end);
%%%Assume now that a1 = 0
H = H(:,2:end);
coeffs = inv(H)*K
%%%Get all your A's,B's, and C's
A = [0;coeffs(1:n-1)]
B = coeffs(n:2*n-1)
C = coeffs(2*n:end)
%%%%Plot the results
for idx = 1:n
xspline = linspace(X(idx),X(idx+1),10);
yspline = A(idx)*xspline.^2 + B(idx)*xspline + C(idx);
p2 = plot(xspline,yspline,'r-','LineWidth',2);
end
legend([p0 p1 p2],'Measured Data','Linear Spline','Quadratic Spline')

[@ysabellebiancaviray1642]

Monte Carlos nice

[@user-ny6wn3lg4x]

write a MATLAB strip to solve the polynomial
p(x)=2x^5-3x^4+7x^3-x^2+5x-6=0
Can you please help me with this?

[@CarlosMontalvo251]

Can you use the fzero function?

[@luvnaangel]

plz can you do for a cubic spline using large yields data for estimating yields curve.I am having many difficulties in estimating yield curve.Would be grateful to you.Thank you

[@cjcar178]

It's on my to-do list. Cubic splines are just very complex so I haven't gotten around to it. I will try and upload it this weekend if I have time.

[@CarlosMontalvo251]

@@cjcar178 ruclips.net/video/gfSKOfHRooQ/видео.html

[@deehanchowdhury1230]

I need a help regarding how to import csv data without empty cells....please make a video on that cause only reading csv data is explained in thousand ways over net but how to deal with the blank cells in csv file isn't explained anywhere...at least i didn't find it.

[@CarlosMontalvo251]

Can you copy and paste an example csv file?

[@CarlosMontalvo251]

Have you tried this? ruclips.net/video/_Lnnw9WLntE/видео.html

[@CarlosMontalvo251]

or this? ruclips.net/video/L-pBWbNWJtY/видео.html

[@deehanchowdhury1230]

www.sharecsv.com/s/e850a3da764bb3c44f71e03482117670/shampoo.csv

[@deehanchowdhury1230]

Actually i solved it in a naive way....using for loop and checking for values ~=0, if this condition was satisfied then i copied data in a new vector.

[@musafir1068]

plz do it for cubic spline

[@CarlosMontalvo251]

adnan najum sure. I'll add it to my to-do list

[@CarlosMontalvo251]

ruclips.net/video/gfSKOfHRooQ/видео.html

[@wafaaali8974]

Please give me away program the solve of the linear and quadratic splines please.

[@CarlosMontalvo251]

All my codes on splines are in this folder as of 6/14/2021
github.com/cmontalvo251/MATLAB/tree/master/Screen_Cast_Codes/Interpolation

[@wafaaali8974]

@@CarlosMontalvo251 thank you so much 🌹🌹

[@sa.75-kin_]

Can you email

[@CarlosMontalvo251]

I prefer to respond to youtube comments.