Keep getting the "Array indices must be positive integers or logical values." error
1 view (last 30 days)
Show older comments
Trying to simulate a water rocket using matlab, however I can't get my for loop to work properly.
This is what I have so far:
close all
clear all
P0 = 6e5; %Pa
Pout = 1e5; %Pa
V0 = 2; %l
V = 1.5; %l
gamma = 1.4;
rho_w = 998; %kg/m^3
%Pin = P0*(V/V0).^-gamma;
dt = 0.01;
t = 1:dt:100;
Ve(1) = 0; %m/s
Pin(1) = 6e5; %Pa
v0 = 0; %m/s
v = 0; %m/s
M0 = 0.1; %kg
M = M0 + (V0-V)*rho_w;
for i = 1:100
Pin(i+1) = Pin(i) - P0(V/V0).^-gamma;
Ve(i+1) = sqrt(2*(Pin(i) - P0)/rho_w);
%v = Ve*log(M0/M) + v0;
end
Really hoping one of you can enlighten me, because I'm completely lost here.
3 Comments
Image Analyst
on 12 Dec 2018
V/V0 = 1.5/2, not 0/0
madhan's Answer below lets the code run without error. No guarantee about the equations correctness though - I didn't try to verify them.
Guillaume
on 12 Dec 2018
Oh! I didn't see that there were both V and V0 variables (uppercase) as well as v and v0 (lowercase).
That's really begging for trouble! You can be sure at some point the wrong case will be used. Never distinguish variable names just by casing.
Accepted Answer
More Answers (0)
See Also
Categories
Find more on Matrix Indexing in Help Center and File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!