i am new to matlab and i want to learn, can anyone help me with this please!!!

I want to write a script which produces the polynomial interpolating the function f(x) = sin(4x) at the points x0 = 1, x1 = 3, x2 = 3.5, x3 = 4.0 by using the Lagrange form of the interpolating polynomial!!!!!!

[Ive J]

https://se.mathworks.com/matlabcentral/answers/305169-what-is-the-code-for-lagrange-interpolating-polynomial-for-a-set-of-given-data

https://se.mathworks.com/matlabcentral/answers/3338-lagrange-interpolation-m

[Anas Gharsa]

thank you so much!!

[Anas Gharsa]

this is what i did

x= [0.9 1.5 2.4 2.6 2.8 3.1 3.5 3.8];

y= [1.0 0.8 1.3 6.2 9.3 6.0 2.1 -0.5];

plot(x,y,'ro');

hold on

p1 = polyfit(x,y,2);

coefficients = polyfit(x, y, 2);

yFit = polyval(coefficients, 2.5);

but it shows like this

why ??did i do something wrong ??

Answer 1

[KSSV]

https://in.mathworks.com/matlabcentral/answers/305169-what-is-the-code-for-lagrange-interpolating-polynomial-for-a-set-of-given-data

https://in.mathworks.com/matlabcentral/answers/3338-lagrange-interpolation-m

https://in.mathworks.com/matlabcentral/fileexchange/65538-matlab-code-for-lagrange-interpolation

And many more just search in google.

[Anas Gharsa]

that was helpful, thank you so much