# Results showing up as NaN

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Alexandru Bortea on 19 Apr 2017
Commented: Andrew Newell on 20 Apr 2017
I have been working on a launch control simulation and something happened recently because the matrix z is returning only NaN values now... I do not remember changing anything in the script or the function. I have also attached below the main function used with the code... maybe you spot a mistake there...
global m g I h lR lF r LCREV_MAX LCSPEED_MAX
LCREV_MAX = 12000;
LCSPEED_MAX = 35;
m = 295; % mass of vehicle including driver
g = 9.81; % gravitational acceleration
r = 0.23; % wheel radius
I = 0.2645; % tyre moment of inertia
h = 0.28; % CoG height
lR = 0.765; % Distance of CoG to rear axle
lF = 0.765; % Distance of CoG to front axel
z10 = 0; % initial x position
z20 = 0; % initial linear velocity
z30 = 0; % initial angle of rear wheel
z40 = 0; % intial angular velocity of rear wheel
z0 = [z10 z20 z30 z40]; % initial conditions vector
t0 = 0; % intial time
tf = 6; % final time
[t,z] = ode45('LC_eom',(t0:0.1:tf),z0);
x = z(:,1); % position as first column of z matrix
v = z(:,2); % linear velocity as second column of z matrix
theta = z(:,3); % angle as third column of z matrix
omega = z(:,4); % angular velocity as fourth column of z matrix
Alexandru Bortea on 20 Apr 2017
Thank you very much for all the answers, I'll try to remove all global parameters and individually use them in the functions.

Andrew Newell on 20 Apr 2017
Here is one source of NaN's: In slipratio_fun with the initial value of t=0 and v=0, you have omega=v=0. The line
sx (abs(omega)*r>=abs(v)) = -1 + v./(omega.*r); % acceleration
sets sz equal to NaN because it's dividing by zero.
Andrew Newell on 20 Apr 2017

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