Simple code for Secant Method

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AV22
AV22 2012-2-26
I was asked to write a simple code for the Secant Method and display results in a table showing Pn, Pn - P* and a few other things. I am trying to get it to solve y = x^2-2. For some reason I can't get my code to perform more than one iteration even though I reassign the variable at the end. Here is my code, and the result I am getting. I need to go to n = 10.
function SecantProject
disp('*******************************')
p0 = 1; p1 = 2; TOL = 0.000001;
for i = 2:10
q0 = f(p0);
q1 = f(p1);
p = p1 - q1(p1-p0)/(q1-q0);
Err = p - sqrt(2);
Alpha0 = abs(p - sqrt(2))/(p0-sqrt(2))^1;
Alpha1 = abs(p - sqrt(2))/(p0-sqrt(2))^1.618;
Alpha2 = abs(p - sqrt(2))/(p0-sqrt(2))^2;
if abs(p-p1)< TOL
q = f(p);
q*q1 < 0;
p0 = p1;
p1 = p;
end
end
fprintf('P0 = %f\n\n', p0)
fprintf('Pn \t\t\t\t Pn-Sqrt(2)\t\t Alpha = 1\t\t Alpha = 1.618\t Alpha = 2\n'); fprintf('__________________________________________________________________________\n')
fprintf('%f \t\t %f\t\t %f\t\t %f\t\t %f\t\t\n', p, Err, Alpha0, Alpha1, Alpha2);
function y = f(x)
y = x^2 - 2;
end
end
And this is the result:
SecantProject
*****************************
P0 = 1.000000
Pn Pn-Sqrt(2) Alpha = 1 Alpha = 1.618 Alpha = 2 ________________________________________________________________________
1.333333 -0.080880 -0.195262 0.12
The formatting looks off on here, but I just need to know how to continue for 8 more iterations?

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