The if loop is continuing even after the condition is false.

I have to find the max value of R in specified range of the SOC values and the answer should be 0.2554 but the if loop is giving answer as 0.2552. The loop is iterating for the values of 'j' even after the condition is false. I have attached the matlab code and the data file.

clear all
clc
load data
Ezero=(0.0026.*temp)+(7.9387*10^(-4).*temp.*SOC)+(0.0016.*temp.*(SOC).^2)+2.5625;   %Open circuit voltage
R=V-Ezero;                                                                         %Battery internal resistance
figure (1)
plot(SOC,V,'-r','LineWidth',1);                                                   %Plot of voltage vs SOC
xlabel('SOC(%)');
ylabel('Voltage(Volts)');
title('Voltage vs SOC plot');
grid on
figure (2)
plot(SOC,Ezero,'-k','LineWidth',1)
xlabel('SOC(%)');
ylabel('Open circuit voltage(Volts)');
title('Open circuit voltage vs SOC plot');                                    %Plot of Open circuit voltage vs SOC
grid on
figure(3)
plot(SOC,R,'-b','LineWidth',1)
xlabel('SOC(%)');
ylabel('Internal Resistance(Ohm)');
title('Internal Resistance vs SOC plot');                                     %Plot of Resistance vs SOC
grid on
%% RUn
socl= find(SOC>=0.6 & SOC<=0.8);
RS=R(socl);
for j=2:length(RS)
   if(RS(j)>RS(j-1))                            %this loop here is giving wrong value
        Rmax=RS(j);                            
    end
end

Answer 1

[KALYAN ACHARJYA]

It's seems perfectly working:

>> RS
RS =
  Columns 1 through 12
    0.2217    0.2226    0.2235    0.2244    0.2252    0.2254    0.2253    0.2252    0.2250    0.2248    0.2245    0.2242
  Columns 13 through 24
    0.2239    0.2236    0.2232    0.2228    0.2224    0.2220    0.2218    0.2216    0.2218    0.2222    0.2225    0.2228
  Columns 25 through 33
    0.2230    0.2233    0.2235    0.2243    0.2252    0.2252    0.2245    0.2237    0.2228
>> length(RS)
ans =
    33

Please note that you have comparing present value with privious one, ant from the array results it shows 15 times present value is greater than privious.

I changed the code here to count how many numbers if condition is true

count=0;
for j=2:length(RS)
   if(RS(j)>RS(j-1))                            %this loop here is giving wrong value
        Rmax=RS(j);  
        count=count+1;
    end
end

Important: Some cases both number (R(j) and R(j-1)) are same till 4th decimal point, in such case I request you to read about floating number representation

One Example:

>> A=2.3456
A =
    2.3456
>> B=3.3456
B =
    3.3456
>> A==B  % Checking wheather A and B equal?
ans =
  logical
   0   

[Deep Shah]

The loop should stop at j=7 (0.2253<0.2254) as the condition is not satisfied but it still continues to check for the relation.

[KALYAN ACHARJYA]

Why do think loop should be stop? "if" any current condition is false, it will check for next R(j) value because of for loop. It doesnot matter whether the codition is true or not, it will check all R(J) values as for loop is running.

Any condition is false, if you want to exit from for loop, please use break statement.

[Deep Shah]

I got the necessary output, Thank you for the help!