Data in array being overwritten when if statement is satisfied.

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Nathan Dick
Nathan Dick 2016-7-27
评论： Stephen23 2016-7-27
The first part of my array Cur2 is populated with 0 as I would expect from the following IF statement. When the IF statement is satisfied and the equation in the ELSE statement is used the first half of the array is overwritten with the value that would be calculated by the eq'n.
clearvars
L=80*10^3; x1=0:1000:1.5*10^5; U= 0.2; t1=x1./U;
Cs= 9; C0= 8;
M0 = 0.75*10^6;
M1= M0;
Q= 50*10^3;
Kr=0.4/24/60/60; Kd=Kr; Ka=0.8/24/60/60;
for n = 1:151
Cur1(1:n) = Kd*M0*(exp(-t1(1:n)*Kr)-exp(-t1(1:n)*Ka))/(Q*(Ka-Kr));
if (n<= 80)
Cur2(1:n) = 0;
else
Cur2(1:n) = Kd*M1*(exp(-((x1(1:n)-L)/U)*Kr)-exp(-((x1(1:n)-L)/U)*Ka))/(Q*(Ka-Kr));
end
C(1:n) = Cs - Cur1(1:n) - (Cs- C0)*exp(-t1(1:n)*Ka)-Cur2(1:n);
end
plot(x1,C);

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Stephen23
Stephen23 2016-7-27
编辑：Stephen23 2016-7-27
Your data is being "overwritten" because that is what you wrote your code to do:
Cur2(1:n) = 0;
puts zeros in elements 1 to n. The your else puts something else in elements 1 to n:
Cur2(1:n) = Kd*M1*(...)
What do you want your code to do ?
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Nathan Dick
Nathan Dick 2016-7-27
Thanks again for the reply. That is exactly what I meant. I got the syntax confused as I though by using(1:n) I was simply saying that it was a 1D array. For uni I have done some VB but this current course requires MATLAB so it is a learning experience.

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