# Creating a Loop to calculate 2 varibles and then repeat calculation with new variable values

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Constantinos Yiannakis on 11 Dec 2019
Need to create a script that:
h1,h2 and VFull need to change after every loop. NewVolume, h1New and power should be recorded in a table or in the workspace.
%constants
d = 7.2;
al = 11500;
cd = 0.8;
ct = 0.5;
g = 9.807;
p = 1029;
%Area Of turbine = pi*r^2
A = 40.715;
%Variables that need to change after every loop
h1 = 14.05; %h1 should be replaced with h1New after every 1 loop
h2 = Height(4851:21600,:); %this data is from a data excel sheet
VFull = 161575; %VFull shoule be replaced by NewVolume after every 1 loop
for c=1:16749 %loop needs to be repeated 16759 times
%Discharge
discharge(c) = cd*A*(sqrt(2*g(h1-h2)))
V = discharge/A
%Power
Power = (1/2)*ct*p*A(V^3)
%New Volume Calculation
NewVolume = VFull - discharge
%New h1
h1New = (VFull - discharge)
end

Jakob B. Nielsen on 11 Dec 2019
You want to index your outputs, such that every iteration becomes that iteration numbers index in an array, instead of having the output as singles.
Your script also had several mistakes in it with taking the square root of a number that could become negative (the abs function prevents this), and several other small things. I changed some things around and now it at least gives an output - play around with it a little and see if you cant get it to do what you want.
%constants
d = 7.2;
al = 11500;
cd = 0.8;
ct = 0.5;
g = 9.807;
p = 1029;
%Area Of turbine = pi*r^2
A = 40.715;
%Variables that need to change after every loop
h1 = 14.05; %h1 should be replaced with h1New after every 1 loop
h2 = Height(4851:21600,:); %this data is from a data excel sheet
VFull = 161575; %VFull shoule be replaced by NewVolume after every 1 loop
for c=1:16749 %loop needs to be repeated 16759 times
%Discharge
discharge(c) = cd*A*(sqrt(2*g*((abs(h1-h2(c)))))) ;
V = discharge(c)/A;
%Power
Power = (1/2)*ct*p*A*V^3;
%New Volume Calculation
NewVolume(c) = VFull - discharge(c);
VFull=NewVolume(c);
%New h1
h1New(c) = (VFull - discharge(c));
h1=h1New(c);
end
Constantinos Yiannakis on 11 Dec 2019
That worked like a charm, Thank you!!

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