# How to compare elements in an array?

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Alec Carruthers 2018 年 4 月 6 日
コメント済み: Alec Carruthers 2018 年 4 月 10 日
My for loop cycles through a series of initial CL values and then a lot of calculations are done and I get final values for CL "CL_IC2." I want to see if any of the original CL values are equal to their corresponding CL_IC2 values.
clc;
clear;
%Design Mission
PAX = 250;
Cargo = 8000;
Range = 7000; %N. Miles
DRatio = .9524988;
PRatio = .23590495;
M = .85;
Vapp = 145; %Knots
TOFL = 10500; %Feet
a = 576.4592054; % Speed of Sound at 35,000 ft, KNOTS
V_cr = M*a; %Knots
R_all = Range + 200 + V_cr*.75; % n.miles
% Fuel Fraction for JT8D Engine with "R_all"
WfWto_8D = .49;
C_JT8D = .78; % SFC JT8D
C_JT9D = .61; % SFC JT9D
WfWto_9D = WfWto_8D*(C_JT9D/C_JT8D);
XX = .7; % Percent Max Fuel at Landing
%%%%%%%Values Changed Manually %%%%%%%%%
Abreast = 8; % Tested 4 - 8
N_aisle = 1; % Tested 1 & 2
Sweep = 30; % Degrees, Tested: 25, 30, 35, 40
AR = 8; % Tested: 6-9
Airfoil = 1; % Supercritical = 1, Conventional = 2.
% Assuming a Cl value so need a for loop.
CL=[.45:.01:.58];
n = length(CL);
DelM = cell(1,[]);
syms x
syms y
for i= 1:n
if Airfoil == 1 % Supercritical
DelM{i} = vpasolve((CL(i)==((-2*10^9)*x^6)-((1*10^8)*x^5)-((2*10^6)*x^4)-((2632.1*x^3)+124.37*x^2)-(5.8637*x)+.5475),x,[-.01 .015]);
end
if Airfoil == 2 %Conventional
DelM{i} = vpasolve((CL(i)==(-5.1087*x^2)-(2.9657*x)+.5509),x,[-.02 .04]);
end
NewDelM=cell2sym(DelM,'f');
MDiv=(M+.004)-NewDelM;
if Airfoil == 1
if Sweep == 25
%tc(i) = solve((y == (135.46.*(MDiv(i)).^4)-(449.48.*(MDiv(i)).^3)+(561.45.*(MDiv(i)).^2)-(313.45.*MDiv(i))+66.196),y);
tc(i) = solve((y == (3.7229.*(MDiv(i)).^2)-(6.7143.*MDiv(i))+3.1025));
end
if Sweep == 30
%tc(i) = solve((y == (339.86.*(MDiv(i)).^4)-(1139.2.*(MDiv(i)).^3)+(1434.1.*(MDiv(i)).^2)-(804.35.*MDiv(i))+169.83),y);
tc(i) = solve((y == (3.9755.*(MDiv(i)).^2)-(7.3602.*MDiv(i))+3.4805));
end
if Sweep == 35
%tc(i) = solve((y == (1098.2.*(MDiv(i)).^4)-(3728.7.*(MDiv(i)).^3)+(4751.1.*(MDiv(i)).^2)-(2693.7.*MDiv(i))+573.67),y);
tc(i) = solve((y == (6.2186.*(MDiv(i)).^2)-(11.535.*MDiv(i))+5.43));
end
if Sweep == 40
%tc(i) = solve((y == (13.242.*(MDiv(i)).^2)-(24.825.*MDiv(i))+11.718),y);
tc(i) = solve((y == (13.242.*(MDiv(i)).^2)-(24.825.*MDiv(i))+11.718));
end
end
if Airfoil == 2
if Sweep == 25
tc(i) = solve((y == (-.5307.*MDiv(i))+.5181),y);
end
if Sweep == 30
tc(i) = solve((y == (-.5037.*MDiv(i))+.5051),y);
end
if Sweep == 35
tc(i) = solve((y == (-.4671.*MDiv(i))+.4854),y);
end
if Sweep == 40
tc(i) = solve((y == (-.4267.*MDiv(i))+.4632),y);
end
end
Par = (cosd(Sweep)^2).*((tc).^2)*AR;
% Need the low speed CL_max_to and CL_max_ld. Use Figure 3 with "Par."
CL_TO(i) = solve((y == (-30.959.*(Par(i).^2))+12.965.*(Par(i))+1.1735),y);
CL_LD(i) = solve((y == (-23.26.*(Par(i).^2))+11.166.*(Par(i))+2.1806),y);
WS_LD(i) = ((Vapp/1.3)^2).*(CL_LD(i))*(DRatio/296);
WS_TO(i) = (WS_LD(i)./(1-(XX*WfWto_9D)));
WS_IC = .965.*WS_TO;
% Initial Cruise CL
CL_IC = (WS_IC./(1481*PRatio*((M)^2)));
CL_IC1 = double(CL_IC);
CL_IC2 = round(CL_IC1,3)
%if CL(i) == CL_IC2
% CL_f = CL
%else
% CL_f = 0
%end
end
%end
You don't really need to worry about the middle just right before the for loop starts and the last few lines. Thank you.

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### 回答 (1 件)

Prajit T R 2018 年 4 月 9 日
Hi Alec
You can use the 'find' function to obtain the values which are common between two arrays. For example:
a=[1 2 3 4]
b=[5 2 3 7]
find(a==b)
The above code returns:
ans =
2 3
In your case, this would be find(CL==CL_IC2)
I hope this helps.
Cheers

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Alec Carruthers 2018 年 4 月 10 日
Alright, I will try that.
Thanks, Alec

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