Code taking too long to execute

I'm ploting a 3d graph of displacement of single degree of freedom system against a loading of sin wave.

First I inputed the function. It has its value in terms of a and b. I calculated a and b as initial conditions were given for the function. The final equation I get is only in form of variables x(time) and y(beta).

I have to plot a 3d graph against them. For this I have to mesh x and y and equate z to my displacement function.

But the program is taking too long to process the part where I equate z to the displacement function (i.e. z=double(G(xx,yy));). I have almost zero background in programming. What changes can I make so that matlab takes less time to execute this part?

Here is my code

clear
clc
syms w wd x a b zai wbar eq1 eq2 u0 v0 y z xx yy
zai=0.05;
po=1000;
k=40609481.90;
m=12000;
w=sqrt(k/m);
wbar=y*w;
wd=w*sqrt(1-zai^2);
F(x,y)=exp(-zai*w*x)*(a*cos(wd*x)+b*sin(wd*x))+po/k*1/((1-y^2)^2+(2*zai*y)^2)*((1-y^2)*sin(y*w*x)-(2*zai*y)*cos(y*w*x));
F(0,y);
derivF(x,y)=diff(F(x,y),'x');
%derivF(0,y);
eq1=F(0,y)==0;
eq2=derivF(0,y)==0;
sol=solve([eq1,eq2],[a,b]);
%sol.a;
%sol.b;
avalue=sol.a;
bvalue=sol.b;
G(x,y)=subs(F(x,y),[a,b],[avalue,bvalue]);
%G(x,y);

%double(G(0.003,0.05));

x=0:0.005:2.5;
y=0:0.005:2.5;

[xx,yy]=meshgrid(x,y);

z=double(G(xx,yy));

figure
surf(xx,yy,z)
shading interp

Answer 1

[Ive J]

Replace this line

z = double(G(xx, yy));

with these

G = matlabFunction(G); % generate a function handle from your symbolic G
z = G(xx, yy);

[Osama Anwar]

Thanks man it resolved my problem.