Why is this While Loop not running?

Question

Benjamin 2024-5-7

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2115836-why-is-this-while-loop-not-running

编辑： Walter Roberson 2024-5-7

Hi all,

I'm doing a spacecraft link budget analysis in MATLAB. I have a function that calculates the link margin, which I call in a main script. As I wish to limit the margin to a certain range I use a While Loop that alters the transmission power (P_t) until the condition is satisfied.

P_t=5;
flag_para=0;
flag_helix=0;
flag_horn=0;
flag_array=1;
S=S_epsilon*1000;
R_b=20e+6;
BER=8e-6;
dl=3;
A=0.1;             % phase array
D_t=0;             % Parabolic  
eta=0.7;
f_t=8e+9;
lamda=3e+8/f_t;    % Operating Wavelength in metres
L_com=0;            % horn
margin=-inf;
j=1;
while margin<6 && margin>12
    [margin,M_com,P_com,L_ant]=comm_payload(flag_para,flag_helix,flag_horn,flag_array...
        ,P_t,eta,lamda,D_t,f_t,L_com,A,S,dl,R_b,BER);
    if margin<6
        P_t=P_t*1.1;
        j=j+1;
    elseif margin>12
        P_t=P_t*0.9;
        j=j+1;
    end
end

This doesn't seem to be working. The code runs but J stays at 1 and the margin also remains at -inf. Any ideas what is wrong? The function 100% works, tested it many times without the while loop.

Cheers