The intent of your code is not clear, though it is likely that your problems lie in the line
phi(m1+1)=(Vplus-Ve)+Vg;
The variables m1 and Vplus are never defined. Also, you say the loop is supposed to be doing some sort of reduction, but there is no reduction operation anywhere to be seen. A reduction variable would appear on both sides of an update, as in,
X=X+1;
However, here is my best guess as to what you might be trying to do:
mvals=round(0.1*(0.1:0.1:v));
parfor i=1:length(mvals);
m=mvals(i);
J= (phi(m))^2*exp(-1/phi(m));
k=J*sigma/q;
Vg=v-t;
Ve= V*(1-exp(-k*t))/2;
subs(i)=m+1;
vals(i)=(Vplus-Ve)+Vg;
end
result=accumarray(subs,vals)
