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Matlab question

Asked by Andrew Rizk on 23 Nov 2011

Hey guys so this is the question. I just need the matlab code for neville's method and newton's divided differences method because i always get errors on matlab.

For general cases, IL can be calculated by
IL = integration from λ min to λ max of F (λ)dλ.
For example, Table is the set of data: F (λ) vs. λ.
values  of λ (×10^−7) = 4.5 4.6 4.7 4.8 4.9 5.0 5.1 5.2 5.3
values of F (λ) (×10^3) = 2.6 2.3 1.8 1.5 0.9 0.2 −0.7 −1.4 −2.
Calculate P8(λ) at λ = 4.55, 4.65, 4.75, 4.85, 4.95, 5.05, 5.15, 5.25 (×10^−7)
by Neville’s algorithm and Newton’s divided differences with the data
given in the Table, where P8(λ) is the Lagrange interpolating polynomial of degree ≤ 8. Which one is faster?
Hint: Commands tic and toc can be used to record the CPU time in
Matlab.

Please I need help as I didn't use matlab before. I just need the matlab codes for these. Thanks

6 Comments

Walter Roberson on 23 Nov 2011

Quite a lot of programming involves implementing known algorithms, and a lot of the rest of programming involves first inventing new algorithms and then implementing them.

If your version of the code is giving problems, then it is time to start to learn how to understand error messages and to read reference material, and to learn how to debug problems.

Start with the first error message that you are having difficulty understanding. Have you search mathworks.com for more information about what that particular error message means?

Andrew Rizk on 25 Nov 2011

ok I have freemat.. i want to find P8(λ) by neville's algorithm...
the input is numbers x0, x1, x2 ..... xn and values f(x0), f(x1), .....f(xn) as the first column Q0,0 Q1,0 .... Qn,0

I want to input some values of x and some values of f(x) but I dont know how to.
so the input would

For i = 1, 2, 3, 4, 5, 6, 7, 8, 9
for j = 0, 1, 2, 3, 4, 5, 6, 7, 8, 9

set Qi,j = [(x - xi,j) * Qi,j-1 - (x-xi) * Qi-1,j-1] / xi - xi,j

OUTPUT (Q);
STOP.

Daniel on 26 Nov 2011

You might have better luck asking in a FreeMat forum, because that syntax doesn't look anything like MATLAB syntax.

Andrew Rizk

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