problem executing while loop
显示 更早的评论
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
采纳的回答
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
GreGG
2012-10-9
Azzi Abdelmalek
2012-10-9
编辑：Azzi Abdelmalek
2012-10-9
No, it enter the loop once, check the value of x. t's changed de tol. The problem is in your code, or it depends on the value of a and x
Azzi Abdelmalek
2012-10-9
initialize n to x
n=x
GreGG
2012-10-9
Azzi Abdelmalek
2012-10-9
does'nt mean there is an error in your code.
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
2012-10-9
更多回答（2 个）
Sachin Ganjare
2012-10-9
0 个投票
n should be initialized with proper value, probabaly zero.
Hope it helps
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)
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