matlab画图老画不好

clear;
clc;
syms T k v b P a p t G V;
a=1;
b=1;
k=1;
T=0.1:0.1:5;
P=0.1:0.1:5;
[X,Y]=meshgrid(T,P);
v=zeros(50,50);
for i=1:50
p=P(1,i);
for j=1:50
t=T(1,j);
eqn=pV^3-(kt+bp)V^2+aV-ab==0;
s=double(solve(eqn,V,'real',true));
v(i,j)=s;
end
end
G=zeros(50,50);
for i=1:50
p=P(1,i);
for j=1:50
t=T(1,j);
V=v(i,j);
G(i,j)=-kt(1+log((V-b)t^(3/2)))-a/V+pV;
end
end
figure
surf(P,T,G);

2.10的式子里面的v是由2.2式求出来的，然后要画2.10那个式子的三维图像