Index exceeds matrix dimensions.

clc; 
clear all; 
close all;
g = 1;
m = 1;
M = 1;
T = 1;
fun = @(x,y,V,T) ((2*pi*g*(1-(V.^2)).^2)/m^2).*y.*(((x-(m*V./sqrt(1-V.^2))).^2./(1-(V).^2))+y.^2).*exp(-(sqrt(m^2+x.^2+y.^2)-M)/T);
QQ_pl = @(V,T) integral2(@(y,x) fun(x,y,V,T), 0, inf, -inf, m*V./sqrt(1-V.^2));
QQ_mi = @(V,T) integral2(@(y,x) fun(x,y,V,T), 0, inf, m*V./sqrt(1-V.^2), inf);

V(1)=0.1
L=0;
dL=0.01;
t(1)=L+dL;
dV(1)=(QQ_mi(V(1),T(1))-QQ_pl(V(1),T(1)))*t(1)

for i=2:50
    t(i)=L+i*dL;
    dV(i)=(QQ_mi(V(i-1),T(i-1))-QQ_pl(V(i-1),T(i-1)))*t(i)
    V(i)=V(i-1)-dV(i)
end
plot(t,V)

Answer 1

[Cris LaPierre]

You define T as a scalar

T = 1

but then in your for loop try to index out values from it like it is a vector

dV(i)=(QQ_mi(V(i-1),T(i-1))-QQ_pl(V(i-1),T(i-1)))*t(i)

You will therefore get this error message any time i>2 (since index is T(i-1)).

Just like you add values to V in each loop, you likely need to do something similar for T.