MATLAB: Help with using arrays to create variables

arraysvariables

I'm trying to use arrays to create variables related to 32 different satellites (which I currently have fully written out it's awful making changes) orbiting a planet and am getting stuck quite early on. As a small example I'm trying to get working, I've got two angles for each satellite (being done in blocks of 8), th0(i) and th(i). The angle th0 works fine, however th relies upon th0 and a parameter, also an angle, called M, which relies on time. As I have 148 timesteps, M is a 148×1 array. When I input my code below, I get an error about the element numbers not matching up. I tried using the transverse of th and th0 but no joy. Can anyone suggest my next move?
%%Relevant parameters
timestep = 600;
G = 6.67408*10^-11;                  %[m^3kg^-1s^-2]
%   Mars data
    Mars.m  = 6.39*10^23;            %[kg]
    Mars.mu = Mars.m*G;              %[m^3s^-2]
    Mars.r  = 3389.5*10^3;           %[m]


    Mars.v  = 241.17;                %[ms^-1]
    Mars.T  = (2*pi*Mars.r)/Mars.v;  %[s]

    Mars.o  = Mars.v/Mars.r;         %[rads^-1]
    Mars.th = Mars.o*timestep;       %[rad] for every second
t = (0:timestep:Mars.T)';        %Mars.T, Length of martian day in seconds
H1 = 9610.5*10^3;               %[m]
a1 = Mars.r + H1;               %[m]
T1 = 2*pi*sqrt(a1^3/Mars.mu);   %[s]
n1 = (2*pi)/T1;                 %[kms^-1]
M1 = n1*t;                      %[rad]
%%Test Section
th0 = zeros(1,length(t));
th = zeros(1,length(t));
for i = 1:8
    th0(i) = deg2rad(45*(i-1));
    th(i) = th0(i) + 2*atan(tan(M1/2));
end

Best Answer

Hi,
try:
%%Relevant parameters
timestep = 600;
G = 6.67408*10^-11;
%   Mars data
    Mars.m  = 6.39*10^23;            %[kg]
    Mars.mu = Mars.m*G;              %[m^3s^-2]
    Mars.r  = 3389.5*10^3;           %[m]


    Mars.v  = 241.17;                %[ms^-1]
    Mars.T  = (2*pi*Mars.r)/Mars.v;  %[s]

    Mars.o  = Mars.v/Mars.r;         %[rads^-1]
    Mars.th = Mars.o*timestep;       %[rad] for every second
t = (0:timestep:Mars.T)';        %Mars.T, Length of martian day in seconds
H1 = 9610.5*10^3;               %[m]
a1 = Mars.r + H1;               %[m]
T1 = 2*pi*sqrt(a1^3/Mars.mu);   %[s]
n1 = (2*pi)/T1;                 %[kms^-1]
M1 = n1*t;                      %[rad]
%%Test Section
th0 = zeros(1,length(t));
th = zeros(1,length(t));
for i = 1:148
    th0(i) = deg2rad(45*(i-1));
end
th = th0'+ 2*atan(tan(M1/2));
Best regards
Stephan
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