I am trying to do an iteration loop, but it repeats iteration 2. What happens???

The problem should be in the if loop in the middle.

clc
clear all
format long
number_of_sites = 3;
r1 = rand(number_of_sites, 1);
sumr=sum(r1);
r2=r1./sumr;
x = [0:1:100];
y(1) = 1;
 i = 1;
 size(x);
J=[ 0.006 45.24; 0.008 43.96; 0.016 40.48; 0.023 38.81; 0.031 37.74; 0.039 37.17; 0.051 36.78; 0.072 36.64; 0.098 36.71];
energy=[1: 1: 100]'*10^-3;
am=5.5*10^-19;
sigma=10^-4;
macroscopicenergies = [30 40 50]*10^-3;
number_of_probes=5;
probes_energy = [10 20 30 40 50]'*10^-3 ;
[alpha, probes]=size(probes_energy);
kb=1.3806488*10^-23;
T=300;
q1=exp((2*am*((probes_energy(1,:).*energy).^0.5)/(kb*T)));
q2=exp((2*am*((probes_energy(2,:).*energy).^0.5)/(kb*T)));
q3=exp((2*am*((probes_energy(3,:).*energy).^0.5)/(kb*T)));
q4=exp((2*am*((probes_energy(4,:).*energy).^0.5)/(kb*T)));
q5=exp((2*am*((probes_energy(5,:).*energy).^0.5)/(kb*T)));
sumq1=sum(q1);
sumq2=sum(q2);
sumq3=sum(q3);
sumq4=sum(q4);
sumq5=sum(q5);
qq1=q1./sumq1;
qq2=q2./sumq2;
qq3=q3./sumq3;
qq4=q4./sumq4;
qq5=q5./sumq5;
while (i<max(size(x)));
        dp0=10^-3;
n=[1:1:i];
if i==1;

sf1(i,:)=(((r2(1))/(sigma*((2*pi)^0.5)))*exp(-0.5*(((energy-macroscopicenergies(1))/sigma).^2)));

else
    if i>=2

      sf1(i,:)=((((r2(1))/(sigma*((2*pi)^0.5)))*exp(-0.5*(((energy-macroscopicenergies(1))/sigma).^2)))-sssa(:,i-1));
      end
  end
  f1=sf1';
  f1q1(:,i)=(f1(:,i)).*qq1;
  f1q2(:,i)=(f1(:,i)).*qq2;
  f1q3(:,i)=(f1(:,i)).*qq3;
  f1q4(:,i)=(f1(:,i)).*qq4;
  f1q5(:,i)=(f1(:,i)).*qq5;
  sf1q1(i,:)=sum(f1q1(:,i));
  sf1q2(i,:)=sum(f1q2(:,i));
  sf1q3(i,:)=sum(f1q3(:,i));
  sf1q4(i,:)=sum(f1q4(:,i));
  sf1q5(i,:)=sum(f1q5(:,i));
  f1q1t(:,i)=((f1q1(:,i))./sf1q1(i,:))*dp0;
  f1q2t(:,i)=((f1q2(:,i))./sf1q2(i,:))*dp0;
  f1q3t(:,i)=((f1q3(:,i))./sf1q3(i,:))*dp0;
  f1q4t(:,i)=((f1q4(:,i))./sf1q4(i,:))*dp0;
  f1q5t(:,i)=((f1q5(:,i))./sf1q5(i,:))*dp0;

sPu10(:,i)=0.2*(f1q1t(:,i)+ f1q2t(:,i)+ f1q3t(:,i)+ f1q4t(:,i)+ f1q5t(:,i));
ssPu10=sPu10';
ssa=zeros(100,101);
ssa(:,n)=sum(sPu10(:,i));
sssa=ssa(:,n);

%sa=[sum(Pu10(n,:))]'
     i = i + 1;
end
My code is as follow, the problem should arise from the if loop in the middle.

Answer 1

[Image Analyst]

Put this line right after the while statement and you'll see that iteration 2 does NOT get repeated.

fprintf('Iteration #%d\n', i);

In the command window...

Iteration #1
Iteration #2
Iteration #3
Iteration #4
Iteration #5
Iteration #6
Iteration #7

and so on.

[Efty Hadjittofis]

Thanks for that. However, my problem is that the results of the second iteration repeated until n=100.

[Image Analyst]

Explain how. The second iteration is not repeated and no results are ever shown in the command window or a GUI. I'm not even sure which of those variables you are calling "the results". Try this:

http://www.mathworks.com/matlabcentral/answers/6200-tutorial-how-to-ask-a-question-on-answers-and-get-a-fast-answer

[Star Strider]

When I ran it, sf1 (using plot) and sssa (using surfc) never changed.

[Efty Hadjittofis]

Yes, that's what I am confused about. The main ideal of the script can be outlined as follow:

1. Insert your data
2. Calculate f(1)
3. Using f(1) calculate δP(1)
4. Perform f(2)=f(1)-δP(1)
5. Repeat 2-4 until f(100)

However something is going wrong with my loops.

[Image Analyst]

What variable in your program is δP?

[Efty Hadjittofis]

In this script δP corresponds to sssa.

[Image Analyst]

What can you learn if you step through it one line at a time? http://blogs.mathworks.com/videos/2012/07/03/debugging-in-matlab/