Why do I get error undefined function or variable?
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% Runge Kutta
h = 0.1;
t1 = 0:h:50;
n = length(t1);
v1 = zeros(1,n);
v1(1)=0;
for i = 1:n-1
k1 = velocity1(t1(i),v1(i));
k2 = velocity1(t1(i)+h/2,v1(i)+0.5*k1*h);
k3 = velocity1(t1(i)+h/2,v1(i)+0.5*k2*h);
k4 = velocity1(t1(i)+h,v1(i)+k3*h);
v1(i+1) = v1(i) + (k1+2*k2+2*k3+k4)*h/6;
if ( abs(v1(i+1))<0 || ~isreal(v1(i+1)) )
tf = t1(i);
break
end
end
vel1_RK4 = v1(1:i);
t1_RK4 = t1(1:i);
h = 0.1;
t2 = 50:h:330;
n = length(t2);
v2 = zeros(1,n);
v2(1) = 10;
for i = 1:n-1
k1 = velocity2(t2(i),v2(i));
k2 = velocity2(t2(i)+h/2,v2(i)+0.5*k1*h);
k3 = velocity2(t2(i)+h/2,v2(i)+0.5*k2*h);
k4 = velocity2(t2(i)+h,v2(i)+k3*h);
v2(i+1) = v2(i) + (k1+2*k2+2*k3+k4)*h/6;
if ( abs(v2(i+1))<0 || ~isreal(v2(i+1)) )
tf = t2(i);
break
end
end
vel2_RK4 = v2(1:i);
t2_RK4 = t2(1:i);
figure
plot (t1_RK4,vel1_RK4,t2_RK4,vel2_RK4)
xlabel( 'Time(s)' )
ylabel( 'Velocity (m/s)' )
title( 'Velocity VS Time using Runge-Kutta' )
legend( 'V1(Before ShutDown)' , 'V2 (After ShutDown)' )
2 Kommentare
Antworten (1)
Shashank Gupta
am 12 Okt. 2020
you haven't define some variable in your code. these error occur when compiler trying to access a function or variables and it is not defined. Do check your code and see if all variable are properly declared. From the first look, "velocity" does seems like not defined. check other variable too.
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