MATLAB: Make an array from function input and output

arrayfunctiongraph

I have a function that inputs velocity and angle, and outputs the distance the ball travels. Function below:
function distance = DTask1_f (v, angle)
h = 1.5;
g = 9.8;
t = linspace (0,10,1000);
x=v*cos(angle*pi/180)*t;
y=h+v*sin(angle*pi/180)*t-0.5*g*t.^2;
ind = find (x == min(x(y<0)));
fprintf ('The ball hits the ground at a distance of %5.4f meters.', x(ind));
distance = x(ind);
end
I now need to write a script that uses the function, and while using a set value for velocity, will graph angle and distance over a set of angles. My script so far:
for angle = 10:13
    v  = 4;
    y = DTask1_f (v, angle);
    x = [angle];    
      a = [x;y]
end
figure
plot(x,y)
xlabel('Angle (deg)');
ylabel('Distance (m)');
title('Ball Trajectory');
I think I need to first make an array using the angle (input) and distance (output), and then graph the array, but im not sure how to make the array. At the moment, it only gives me the last two points.
Apologies if this is a simplistic question, but thanks for the help.

Best Answer

Hi,
use:
angle_range = 10:1:13
for k = 1:length(angle_range)
      v = 4; 
      a(k,2) = DTask1_f (v, angle_range(k))
      a(k,1) = angle_range(k)
end
figure 
plot(a(:,1),a(:,2)) 
xlabel('Angle (deg)');
ylabel('Distance (m)');
title('Ball Trajectory');
If you want to extend or vary the range of angle or make other stepsize for angle modify first line.
Best regards
Stephan
Related Question