MATLAB: When calculating a double integral, matlab does not give a numeric result

numerical integrationsymbolic

I want to evaluate a double integral over y and z using the symbolic toolbox. But when I evaluate the integral over y, the sevond integral it gives me the result in function of another integral. Even when I use vpa or double it still gives me the solution in terms of the integral. Can somebody help me with this problem? 
clc 
clear all
close all
syms y z
syms a c G theta k Y
f = (a^2-y^2+c*z^2)*(a^2+c*y^2-z^2);
f = subs(f,c,3-2*sqrt(2));
Cte = -(G*theta)/(a^2*(1-sqrt(2)));
cc =3-2*sqrt(2);
%%% Bounds for Z
 Z1 = y;
 Z2 = sqrt(a^2+cc*y^2);
 
 %%% Bound for Y
 Y1 = 0.000001; 
 Y2 = sqrt(a^2/(1-cc));
Mt_0 = int(int(f, z, Z1, Z2),y, Y1,Y2)
solution= int((4889947395900467*a^2*(a^2 + (386347768529971*y^2)/2251799813685248)^(3/2))/6755399441055744 - (386347768529971*(a^2 + (386347768529971*y^2)/2251799813685248)^(5/2))/11258999068426240 - (9991940203577747161783300382167*y^2*(a^2 + (386347768529971*y^2)/2251799813685248)^(3/2))/15211807202738752817960438464512 - a^4*y - (10439733998322027949954816191181*y^5)/76059036013693764089802192322560 + (1865452045155277*a^2*y^3)/1688849860263936, y, 1/1000000, ((2251799813685248*a^2)/1865452045155277)^(1/2))

Best Answer

You need to specify the value of 'a' to get numeric solution
>> vpa(subs(Mt_0, a, 1))
ans =
0.2474375304180263605036809118672
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