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How to create a vector by iteration

Asked by Faouzi Gheffar on 21 Jun 2019
Latest activity Edited by Jan
on 21 Jun 2019
Accepted Answer by Jan
Hello everyone,
I am new on Matlab and I have some questions about a program I am making.
I am working on a program that creates a vector from tthree other vector by iterations with the following formula :
I would like to create the vector F whcih represent a baseline calculated by iteration from P1, P2 and G which also are vectors with the same number of elements.
Here are the steps I have to follow :
1. Define the vectors, G(t), Pl(t) and P2(t), so that all have an equal number of elements.
2. Set F(t) equal to Pl(t) and evaluate the right-hand side of Eq. 3.
3. Set the evaluated F(t) equal to the input F(t) and perform step 2 again. Repeat this procedure until F(t) does not change further when the output of the preceding iteration is put equal to the input of the next.
I am struggling at step 3. I don't know how to create the loop.
Here is my code for the moment :
% Iterative baseline using Bandara method
clear all
close all
dataset = xlsread('ramp.xlsx','A15000:B130000');
% Variables
x = dataset(:,1);
y = dataset (:,2);
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Time vector
t = 27 : 1 : 218;
% Vectors P1 and P2
P1 = 0.000148 + -0.000182 * t.^1;
P2 = 0.027040 + -0.000329 * t.^1;
% Vector G
G = interp1(x,y,t);
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%% Definition of F %%%%%
F0 = P1;
Fnew = zeros(1,length(t));
it = 1; % Iteration number
fun = @(t)G-F0;
while true
for ii = 1 : length(t)
Fnew(ii) = (integral(fun,t(1),t(ii),'ArrayValued',true) / integral(fun,t(1),t(end),'ArrayValued',true)) * (P2(ii) - P1(ii)) + P1(ii);
if Fnew(ii) - F0(ii) < 0.1
break
end
end
F0 = Fnew;
it = it+1;
end
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
hold on
% plot(x,y,'r-','linewidth',2);
plot(t,P1,'linewidth',2);
plot(t,P2,'linewidth',2);
plot(t,G,'linewidth',2);
plot(t,Fnew,'linewidth',2);
Does anyone have an idea of what is wrong with my code ?
You will find enclosed the excel file related to the code.
Thanks in advance for your help.

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1 Answer

Answer by Jan
on 21 Jun 2019
Edited by Jan
on 21 Jun 2019
 Accepted Answer

The break stops the for loop, but there is no exit from the outer while loop:
while true
for ii = 1 : length(t)
Fnew(ii) = (integral(fun,t(1),t(ii),'ArrayValued',true) / integral(fun,t(1),t(end),'ArrayValued',true)) * (P2(ii) - P1(ii)) + P1(ii);
if Fnew(ii) - F0(ii) < 0.1
break
end
end
F0 = Fnew;
it = it+1;
end
Maybe you mean:
proceed = true;
while proceed
for ii = 1 : length(t)
Fnew(ii) = (integral(fun,t(1),t(ii),'ArrayValued',true) / ...
integral(fun,t(1),t(end),'ArrayValued',true)) * ...
(P2(ii) - P1(ii)) + P1(ii);
if Fnew(ii) - F0(ii) < 0.1
proceed = false; % Will stop the WHILE loop
break % exits the FOR loop
end
end
F0 = Fnew;
it = it+1;
end

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