# IF statement to fill a cell array base on conditions

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Jestoni Orcejola on 26 Aug 2020
Answered: Jestoni Orcejola on 2 Sep 2020
I have an ODE function with time dependent variables, one of the time dependent variable I am trying to pass throug the equation is volume. I want to set a an if statement that will fill a cell array that contains volume change over time. What I am have trouble with is writing the proper if statement.
My goal is to change volume for a certain amount of time, in my case I am changing volume until I meet a threshold, then stay constant at that threshold for another prescribed time, then when I crossed a certain depth I want to change volume again until I meet the seond threshold. Once I create this cell array, I wan to pass it to my function.
Here is my code:
DEPTH=y(1);
%% Calculating Displaced Volume as a function of flowrate and time
%cubic meter
VBD_State=cell(length(time),1);
pumprate=23.3/1000000;
total_oil=2600/1000000;
new_total_oil=1300;
for b = 1:length(time)
if displaced_volume(time(b),pumprate)<=total_oil
VBD_State{b,1}=displaced_volume(time(b),pumprate);
end
if DEPTH ==900 && displaced_volume(time(c),pumprate)<=new_total_oil
VBD_State{b,1}=displaced_volume(time(c),pumprate);
else
VBD_State{(b),1}=total_oil;
end
end
end

Ayush Gupta on 2 Sep 2020
Let’s say the two-volume threshold are volume_threshold1 and volume_threshold2, it can be done like this. Refer to the following code:
if(depth < depth_threshold)
if(current_volume < volume_threshold1)
change volume or do whtatever
end
else
if(current volume < colume_threshold2)
change the volume accordingly
end
end
And change the symbols accordingly to fit it.

Jestoni Orcejola on 2 Sep 2020
DEPTH=y(1);
initial_float_volume=0.0939.*ones(length(time),1);
%% Calculating Displaced Volume as a function of flowrate and time
%cubic meter
VBD_State=cell(length(time),1);
pumprate=23.3/1000000;
total_oil=2600/1000000;
new_total_oil=1300;
for b = 1:length(time)
if(DEPTH < 900)
if displaced_volume(time(b),pumprate)<=total_oil
VBD_State{b,1}=displaced_volume(time(b),pumprate);
end
current_v= VBD_State{b,1};
else
if current_v>(.0939+new_total_oil)
VBD_State{b,1}=displaced_volume(time(c),pumprate);
end
end
end
The code above is terminating prematurely.
I need the code to do:
if y(1) < 900
change volume by adding the amount: first threshold
--there is a rate at which the volume changes until it meets the threshold--
then when y(1)=900
change volume by subtracting the amount: second threshold
I need the volume change to be saved in an array to pass through the equation below
%% Function for ODE45: Calculates Velocity
%V=dv;%0.0943912;
Cd=.16;
A=.0613;
m=95.976;
g=9.81;
%density=v(1);
format long g
%Volume as a function of BE
V=spline(time,Float_Volume,DEPTH);
rho=spline(xx,Seawater_Density_Profile,DEPTH) ;
%rho = spline(x1,descending_rho_profile,DEPTH);
speed=[y(2); (rho*V*g)/-(m+V*rho)+(m*g/(m+V*rho))-((1/(2*m+V*rho)*Cd*A.*rho.*y(2).^2))];