Keep getting the "Array indices must be positive integers or logical values." error
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Tom Oud
am 12 Dez. 2018
Kommentiert: Tom Oud
am 13 Dez. 2018
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 Kommentare
Image Analyst
am 12 Dez. 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
am 12 Dez. 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.
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