problem executing while loop

1 次查看（过去 30 天）
GreGG
GreGG 2012-10-9
im writing a script to solve the square root of a number using halley's method
my equations: y=(1/a)*x^2
n = (x/8)*(15-(y)*(10-3*(y)))
then n becomes the new x and the equation repeats
my problem is its not looping it runs through once and then stops
clc
clear
a = input('number ');
x = input('guess ');
tol = 0.0000001;
while (abs(n-x)<=tol)
y=(1/a)*x^2;
n = ((x/8)*(15-(y)*(10-3*(y))));
x=n;
end
disp(n)
i want the loop to stop when the number is accurate to 6 decimal places. what am i doing wrong
very new to ML
  1 个评论
GreGG
GreGG 2012-10-9
ended up figuring it out
clc
clear
a = input('number ');
x = input('guess ');
tol = 0.000001;
dif=inf;
while dif>=tol
y=(1/a)*x^2;
n = ((x/8)*(15-y*(10-3*y)));
dif= (abs(n-x));
disp(n)
x=n;
end
disp(n)

请先登录，再进行评论。

请先登录，再回答此问题。

采纳的回答

Azzi Abdelmalek
Azzi Abdelmalek 2012-10-9
编辑：Azzi Abdelmalek 2012-10-10
insert before while n=x;
clc
clear
a = input('number ');
x = input('guess ');
tol = 0.0000001;
n=x
while (abs(n-x)<=tol)
y=(1/a)*x^2;
n = ((x/8)*(15-(y)*(10-3*(y))));
x=n;
end
disp(n)
  7 个评论
显示 5更早的评论
Azzi Abdelmalek
Azzi Abdelmalek 2012-10-9
but if you want to quit a loop after a certain number of itteration, we can add another condition
GreGG
GreGG 2012-10-9
eventually i want to adjust the code so that the user can decide how many accurate decimal places they get each loop adds 2 correct decimals (or something like that i dont remember right now)...am i on the right track for this?

请先登录，再进行评论。

更多回答（2 个）

Sachin Ganjare
Sachin Ganjare 2012-10-9
n should be initialized with proper value, probabaly zero.
Hope it helps
Amateuromania
Amateuromania 2012-10-9
编辑：Walter Roberson 2012-10-9
You haven't declared n. First calculate n then check the condition much like the do while loop.
You can use something like this:
clc;
clear;
a = input('number ');
x = input('guess ');
tol = 0.0000001;
y=(1/a)*x^2;
n = ((x/8)*(15-(y)*(10-3*(y))));
x=n;
while (abs(n-x)<=tol)
y=(1/a)*x^2;
n = ((x/8)*(15-(y)*(10-3*(y))));
x=n;
end;
disp(n)

类别

在 Help Center 和 File Exchange 中查找有关 Common Operations 的更多信息

标签

Community Treasure Hunt

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

Start Hunting!

Translated by