How to use nested FOR loop to create a matrix of answers?

Hello, I'm relatively new to MATLAB and I'm struggling on producing a matrix with a size of 30x6 using nested FOR loops.

I want 30 different values for the variable 'theta' between 0-90 and 6 different values for the variable 'Vs' between 0-60, put it through the equations and return the answers as a 30 by 6 matrix. I've tried having theta = (3:3:90)' and Vs = 10:10:60 but that's as far as my knowledge goes. I'm not entirely sure where to put the for loops in this code either.

Thanks in advance, I appreciate any kind of help.

% INPUT DATA
% Specified constants:
k = 0.02;
g = 9.81;
dt = 0.01;
% Input the initial condition:
theta = 55;            % Launch angle in degrees.
rads = theta*(pi/180); % Converts degrees to radians.
Vs = 10;               % Launch speed m/s.
u(1) = Vs*cos(rads);
v(1) = Vs*sin(rads);
% Launch pad location:
x(1) = 0;
y(1) = 0;
% Compute approximate solution of the trajecotry of flight.
% Repeat up to 2000 time, i.e., until ball hits the ground.
for n = 1:1:2000
    u(n+1) = u(n)- dt * (k * sqrt(u(n)^2+v(n)^2) * u(n));
    v(n+1) = v(n)- dt * (k * sqrt(u(n)^2+v(n)^2) * v(n) + g);
    x(n+1) = x(n) + u(n) * dt;
    y(n+1) = y(n) + v(n) * dt;
% Determination of when the object hits ground:
    if y(n+1) < 0
        slope = (y(n+1) - y(n))/(x(n+1) - x(n));
        b = y(n) - slope * x(n);
        xhit = - b/slope;
        plot(x,y)
        fprintf(' The length of the shot = %5.2f \n', xhit)
    end
% Once object hits terminate the computations with a break:
    if y(n+1) < 0 
        break;
    end
end

 The length of the shot =  8.27 

Answer 1

[Jan]

thetaL = 3:3:90;
VsL = 10:10:60;
... Other constants
Result = NaN(numel(thetaL), numel(VsL));
for itheta = 1:numel(thetaL)
    theta = thetaL(itheta);
    rads = theta*(pi/180); % Converts degrees to radians.
    for iVs = 1:numel(VsL)
        Vs = VsL(iVs);
        ... Your code:
        u(1) = Vs*cos(rads);
        v(1) = Vs*sin(rads);
        ...
            
        Result(itheta, iVs) = xhit;
    end
end

[Jan]

Hi! Apologies for the late reply and thank you for answering! If it's not too much, do you mind explaining to me what the variables "numel" and iVs" do in this code?

[Jan]

numel is a command, not a variable. See:

help numel
doc numel

iVs is the loop counter of the inner for loop. It is used to obtain the iVs.th element from the vector Vs and to access the iVs.th column of the output Result.

[Julian]

what is the purpose of NaN in this?

[Jan]

Only to fill the output with values initially, which can be recognized. Maybe your code does not find a solution for some inputs.