Problem with looping: the loop does not stop

Question

Anne 2020-4-25

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/520664-problem-with-looping-the-loop-does-not-stop

评论： Anne 2020-4-25

Hello!

I have a problem that I have built a simple loop, which does not stop while running the code. Does anyone know what could be the issu? I have Matlab 2014.

Lw=106.5
hs=80
hr=1.5
a_air=0.0001
La=zeros(1,8000)
d=1:8000
for  i=1:8000
     if i<=1000
         La(i)=Lw - 8 - 20*log(i) - 0.005*i
     else
         deltaLa=10*log(10^(Lw/10)) - 10*log(10^((Lw-sqrt(i)*a_air)/10))
         La(i)=Lw - 8 - 20*log(i) - deltaLa + 10*log(i/1000)
     end  
end

Thank you!

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Muhammad Usman 2020-4-25

在 MATLAB Online 中打开

Why are you using

d=1:8000

for loop check the if condition at every iteration, and will continue for 8000 in total.

So you can skip the for loop and just use 'd' array to compute your results

Lw=106.5;
hs=80;
hr=1.5;
a_air=0.0001;
La=zeros(1,8000);
d=1:8000;
     if d<=1000
         La(d)=Lw - 8 - 20*log(d) - 0.005*d
     else
         deltaLa=10*log(10.^(Lw/10)) - 10*log(10.^((Lw-sqrt(d)*a_air)/10));
         La(d)=Lw - 8 - 20*log(d) - deltaLa + 10*log(d/1000)
     end  

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Answer 1

Jamal Nasir 2020-4-25

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/520664-problem-with-looping-the-loop-does-not-stop#answer_428325

编辑：Jamal Nasir 2020-4-25

在 MATLAB Online 中打开

%%% you can try this it work good %%%%
clc 
clear 
Lw=106.5
hs=80
hr=1.5
a_air=0.0001
d=1:8000
La=[];
for  i=1:8000    
     if i<=1000
         La=[La; Lw - 8 - 20*log(i) - 0.005*i];
    else
         deltaLa=10*log(10^(Lw/10)) - 10*log(10^((Lw-sqrt(i)*a_air)/10))
         La=[La;Lw - 8 - 20*log(i) - deltaLa + 10*log(i/1000)];
     end  
end