Unsure of what is happening in for loop
1 view (last 30 days)
Show older comments
Dear all,
I have the following for loop,
T92to20_state_d = [2.50926000000000; 5.04629166666667; 3.81944833333333];
Rn92to20_state_d = [24.1978271186779; 24.8685463692206; 24.5147611929163];
LvETPM92to20_state_d = [11.5146886953329; 10.5486657087851; 10.7259878112342];
GE92to20_state_d = [-12.3855735457507; -12.1467974925575; -12.2727450153218];
windspd92to20_state_d_2 = [1.64395657249513; 1.16191506903469; 1.62723837006298];
T4 = [276.391481481482; 277.285000000000; 277.706296296296];
Pressure_atmos = [99.189335562566010];
k = 0.35;
z1 = 0.5; z2 = 1.14;
z0 = 0.21756875;
T = T92to20_state_d + 273.16;
H_old = Rn92to20_state_d - LvETPM92to20_state_d - GE92to20_state_d;
H92to20_state_d = H_old;
delta1 = ones(size(H_old));
L = ones(size(1:length(Rn92to20_state_d)+1));
zeta_old = zeros(size(H_old));
l = 0;
for i = 1:3
while delta1(i) > 0.01
u_s(i) = (k.*windspd92to20_state_d_2(i)*0.277778*z1)/(log(z1/z0) - 4.7*zeta_old(i));
L(i) = (T(i)*u_s(i)^3*1010*1.225)/(k*9.81*H92to20_state_d(i));
a(i) = 122.44*Pressure_atmos/T(i);
b(i) = u_s(i)*abs(T4(i) - T(i));
c(i) = 0.74*log(z2/z1) + (4.7/L(i))*(z2-z1);
H(i) = a(i)*b(i)/c(i);
zeta(i) = z2/L(i);
delta1(i) = (L(i+1)-L(i))./L(i);
H92to20_state_d(i) = H(i);
zeta_old(i) = zeta(i);
l = l+1;
end
end
Using manual calculation, I can get the values for i = 1 but not for i = 2 and 3.
% u_s(2) = (k.*windspd92to20_state_d_2(2)*0.277778*z1)/(log(z1/z0) - 4.7*zeta_old(2))
% = 0.2444 (but answer from loop is 0.0679).
% delta1(1) = -0.6625 (but answer from loop is -0.7151)
I can't seem to find the problem. Thank you in advance.
0 Comments
Accepted Answer
Mathieu NOE
on 8 Dec 2021
hello
I don't get why the while loop is for ?
The for loop by itself will generate this result
delta1 =
-0.7151
-0.1559
-0.6961
so the condition while delta1(i) > 0.01 is never met
I a have a feeling the code implementation is maybe not what is should be but I don't understand what is the target here
I beleive the code does even not need that for loop as it should be vectorized
also why have created the variable "l" which is incremented ?
so code sligthly modified for my test purpose
clc
clearvars
T92to20_state_d = [2.50926000000000; 5.04629166666667; 3.81944833333333];
Rn92to20_state_d = [24.1978271186779; 24.8685463692206; 24.5147611929163];
LvETPM92to20_state_d = [11.5146886953329; 10.5486657087851; 10.7259878112342];
GE92to20_state_d = [-12.3855735457507; -12.1467974925575; -12.2727450153218];
windspd92to20_state_d_2 = [1.64395657249513; 1.16191506903469; 1.62723837006298];
T4 = [276.391481481482; 277.285000000000; 277.706296296296];
Pressure_atmos = [99.189335562566010];
k = 0.35;
z1 = 0.5; z2 = 1.14;
z0 = 0.21756875;
T = T92to20_state_d + 273.16;
H_old = Rn92to20_state_d - LvETPM92to20_state_d - GE92to20_state_d;
H92to20_state_d = H_old;
delta1 = ones(size(H_old));
L = ones(size(1:length(Rn92to20_state_d)+1));
zeta_old = zeros(size(H_old));
l = 0;
% for i = 1:3
% while delta1(ci) > 0.01
for ci = 1:3
u_s(ci) = (k.*windspd92to20_state_d_2(ci)*0.277778*z1)/(log(z1/z0) - 4.7*zeta_old(ci));
L(ci) = (T(ci)*u_s(ci)^3*1010*1.225)/(k*9.81*H92to20_state_d(ci));
a(ci) = 122.44*Pressure_atmos/T(ci);
b(ci) = u_s(ci)*abs(T4(ci) - T(ci));
c(ci) = 0.74*log(z2/z1) + (4.7/L(ci))*(z2-z1);
H(ci) = a(ci)*b(ci)/c(ci);
zeta(ci) = z2/L(ci);
delta1(ci) = (L(ci+1)-L(ci))./L(ci);
H92to20_state_d(ci) = H(ci);
zeta_old(ci) = zeta(ci);
l = l+1; % what is the purpose of this ?
end
% end
8 Comments
More Answers (0)
See Also
Categories
Find more on Entering Commands in Help Center and File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!