How to display value of particular iteration in a loop

43 Ansichten (letzte 30 Tage)
Piotr Haciuk
Piotr Haciuk am 14 Aug. 2018
Bearbeitet: Stephen23 am 14 Aug. 2018
I am having a slight problem, I'd like to find a relative error without knowing the analytical solution. I have an equation where i need to find the value of F using composite mid rule when the relative error is less than 1%. Here is my code so far: The equation is F= integral (from 0 to 30) of (200*(z(n)/(5+z(n)))*exp((-2*z(n))/30))dz :
clc
clear all
a=0;
b=30;
s=1000;
dx=(b-a)/s;
z=zeros(1,s);
for n=1:s
z(n)=a+dx/2+(n-1)*dx;
F=0;
for n=1:s
F=F+dx*(200*(z(n)/(5+z(n)))*exp((-2*z(n))/30));
end
sprintf('%6.2f',F)
  6 Kommentare
Piotr Haciuk
Piotr Haciuk am 14 Aug. 2018
How can i find the relative error? the answers i wrote i should expect. When you change the value of s for 100 i get the answer 1480.72, for 200 i get the answer 1480.61, for s=1000 i get 1480.57, but when running it with s=1000 when i want to take the value for n=100 it doesnt give me same answer as for s=100
Piotr Haciuk
Piotr Haciuk am 14 Aug. 2018
Also, at which iteration the relative error of the si=olution is less than 1%

Melden Sie sich an, um zu kommentieren.

Antworten (1)

Alberto Mora
Alberto Mora am 14 Aug. 2018
Maybe you can use this piece of code inside the for loop:
if n==desired_iteration
disp('This is the desired iteration!');
disp(['The result at ',num2str(n),' iteration is ',num2str(result)]);
end
  6 Kommentare
Piotr Haciuk
Piotr Haciuk am 14 Aug. 2018
Torsten, how to implement it to my code?
Torsten
Torsten am 14 Aug. 2018
As you can see from the answer provided in your textbook, the authors seem to define the relative error as
|F_(2*n)-F_n|/|F_n|
So simply calculate F for n and 2*n and evaluate the expression above. If it is less than 0.01, you are done. Otherwise you will have to increase n and repeat the procedure.

Melden Sie sich an, um zu kommentieren.

Kategorien

Mehr zu Loops and Conditional Statements finden Sie in Help Center und File Exchange

Produkte


Version

R2017a

Community Treasure Hunt

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

Start Hunting!

Translated by