Didnot get the value after executing

Question

Maheen Fazal 2019-2-14

0
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https://ww2.mathworks.cn/matlabcentral/answers/444908-didnot-get-the-value-after-executing

回答： Walter Roberson 2019-2-14

Hi Sir,after running this code ,MATLAB didnot display the Rhn answer and typing Rhn in the command window i get undefined variable.Sir kindly specify the error please

close all
clear all
TN=4;
n_vec=1:TN;
simulations=10000;
for n=n_vec
       E=[];
for sim=1:simulations
           B=0.3; %idle period
        phi=(1-B)/n; %backscattering time
        Bbn=20*1000; %transmission rate by backscatter communication
        Rbn =(phi*Bbn); %no of bits transmitted by backscattering in busy period
        
        PT=17*1000; %PT transmit power 17kW
        del=0.6; %delta energy harvesting efficiency 
        No=0.01; %noise power
        d= 8304.215; % distance from PT to ST ,5.16 miles, 8.304215km
        sigma=2.7; %pathloss(db) in urban area cellular radio btw 2.7 ro 3.5
        
         for r=TN;
 g=rand(1,r);
        PRn=((del*PT*g)./(1-d^sigma)*No); %generating negative value due to No
        Kn=0.6; %transmission efficiency
        Bandwidth=100*1000;
        Psi=Kn*Bandwidth; 
        tau=B/n;
        Ehn=((1-B-phi)*PRn);
        E=[E Ehn];
        sorted=sort(Ehn,'descend');
        total=length(sorted);
        half=(total/2);
        max=sorted(1:half);
        min=sorted(half+1:end);
end
for Max=1:max
 rr=TN/2;
h=rand(1,rr);
Rhn=(tau*Psi*log(2))*(1+((max*h)/(tau*No)));
end 
end
end

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Preethi 2019-2-14

Hi,

Check the value of 'max'

Maheen Fazal 2019-2-14

It is giving the value zero for max with the last for loop but when i remove it the max value get changed,i didnot understand how and why

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Answer 1

Walter Roberson 2019-2-14

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/444908-didnot-get-the-value-after-executing#answer_360988

max and min are vectors. When you use a vector as a bound on a for loop, then only the first element in the vector is used.

Your for Max loop is overwriting Rhn in every iteration, so you might as well only use the last iteration.

Naming variables max or min is quite likely to lead to problems later when you try to use max() or min() as functions. At the very least it confuses readers of the code.