Modifying Iteration for Multiple Inputs - matlab

Question

I am doing an iteration to find the corresponding latitude/longitude at a height (h_intercept). My code works perfectly for a single height value. However, I want to find the lat/long of 79 heights (1x79 matrix) and therefore have an output that is a 3x79 matrix (llh_test). I've tried a for loop but I can't seem to get the results I want. I am probably doing something stupid.
Basically, I need to modify it so it will run with rng_sat, u_sat and h_intercept all being 1x79 matrices. It needs to step through the entire iteration before moving to the next values of rng_sat, u_sat and h_intercept
Also, I want to store all of the llh_test values (3x79 matrix)
rng_sat= sat_look_tcs_pass1(3,1)/2e2;
u_sat=[sat_look_tcs_pass1(1,1)/sat_look_tcs_pass1(3,1);sat_look_tcs_pass1(2,1)/sat_look_tcs_pass1(3,1);sat_look_tcs_pass1(3,1)/sat_look_tcs_pass1(3,1)];
h_intercept=sat_look_pass1_llh(3,1)/2e3;
h_test=0;
rng_test_min=0;
rng_test_max=rng_sat;
err=0.01;
while abs(h_test-h_intercept)>err
rng_test=(rng_test_min+rng_test_max)/2;
tcs_test=u_sat*rng_test;
llh_test=tcs2llhT(tcs_test,station_llh);
h_test=llh_test(3,:);
if h_test>=h_intercept;
rng_test_max=rng_test;
else
rng_test_min=rng_test;
end
end

Answer 1

The easiest thing to do here would be to encapsulate this into a single for loop, and change the way you're accessing the core variables so that you're using the loop index instead. Looking at your code, I'm assuming that sat_look_tcs_pass1 is a 3 x 79 matrix. I'm also going to assume that the output height h_test is a single value because when you're doing h_test = llh_test(3,:), h_test will actually become a vector, as you are trying to get all of the columns for the third row. I'm going to assume that this is a single value, rather than an array.
To modify this code, this actually will take no effort at all, so here's where you need to modify. Anywhere you see %// NEW is where I modified and anything else is your original code:
llh_test = zeros(3,79); %// Preallocate
for k = 1 : 79 %// You have 79 values to go through
rng_sat = sat_look_tcs_pass1(3,k)/2e2; %// NEW Change to k
u_sat = [sat_look_tcs_pass1(1,k)/sat_look_tcs_pass1(3,k); ...
sat_look_tcs_pass1(2,k)/sat_look_tcs_pass1(3,k);...
sat_look_tcs_pass1(3,k)/sat_look_tcs_pass1(3,k)]; %// NEW - Change to k
h_intercept = sat_look_pass1_llh(3,k)/2e3; %// NEW - Change to k
rng_test_min=0;
rng_test_max=rng_sat;
err=0.01;
while abs(h_test-h_intercept) > err
rng_test=(rng_test_min+rng_test_max)/2;
tcs_test=u_sat*rng_test;
llh_test(:,k) = tcs2llhT(tcs_test,station_llh); %// NEW - llh_test is now a matrix
h_test = llh_test(3,k); %// NEW - Changed the way we are accessing llh_test
if h_test >= h_intercept
rng_test_max=rng_test;
else
rng_test_min=rng_test;
end
end
end
Take a look at the general pattern of your code. You essentially are changing all of the points where you were accessing the first column with the kth column. Also, llh_test is a matrix, and so for each iteration in your loop, you want to access the kth column. llh_test should now be a 3 x 79 matrix as per your specifications.
Good luck!