I am trying to get an infinite sum using symsum, but when I trying to convert to double I am getting error

%if true
%%%%
clear all
E=0.01;
% t= [0.025 0.05 0.1 0.2 0.3 0.4 1]';
t=[ 0.05];
y=0:0.1:1;
y=y';
syms n
p=(1/(4*pi*pi*E))^0.5;
if floor(p)==p
i=1;
while i<(length(t)+1)
  j=1;
  while j<(length(y)+1)

         S1 = symsum(        (sin( n*pi*y(j))/n)*exp(-0.5*t(i)/E)*(  cosh(0.5*((1-4*n*n*pi*pi*E)^0.5)*t(i)/E)+  ((1/(1-4*n*n*pi*pi*E))^0.5) *sinh(0.5*((1-4*n*n*pi*pi*E)^0.5)*t(i)/E)) , n, 1, p-1) ;      

                    S2 = symsum(        (sin( n*pi*y(j))/n)*exp(-0.5*t(i)/E)*(1+0.5*t(i)/E ) , n, p, p) ;      

           S3 = symsum(        (sin( n*pi*y(j))/n)*exp(-0.5*t(i)/E)*(  cos(0.5*((-1+4*n*n*pi*pi*E)^0.5)*t(i)/E)+  ((1/(-1+4*n*n*pi*pi*E))^0.5) *sin(0.5*((-1+4*n*n*pi*pi*E)^0.5)*t(i)/E)) , n, p+1, inf) ;    
summ=S1+S3+S2;
    u(j,i)= 1-y(j)-(2/pi)*(summ);
    j=j+1;
    end
    i=i+1
end
else 
    i=1;
while i<(length(t)+1)
    j=1;
    while j<(length(y)+1)
        o=floor(p);
          S1 = symsum(        (sin( n*pi*y(j))/n)*exp(-0.5*t(i)/E)*(  cosh(0.5*((1-4*n*n*pi*pi*E)^0.5)*t(i)/E)+  ((1/(1-4*n*n*pi*pi*E))^0.5) *sinh(0.5*((1-4*n*n*pi*pi*E)^0.5)*t(i)/E)) , n, 1, o) ;      
 S3 = symsum(        (sin( n*pi*y(j))/n)*exp(-0.5*t(i)/E)*(  cos(0.5*((-1+4*n*n*pi*pi*E)^0.5)*t(i)/E)+  ((1/(-1+4*n*n*pi*pi*E))^0.5) *sin(0.5*((-1+4*n*n*pi*pi*E)^0.5)*t(i)/E)) , n, o, inf) ;    

        summ=S1+S3;

        u(j,i)= 1-y(j)-(2/pi)*(summ);

    j=j+1;
    end
    i=i+1
end
end
g=double(u);
u=g;
l=[y u];
[g,h]=size(l);
plot(y,l)
figure;
C2 = zeros(g,h);
for I = 1:h,
    C2(:,I) = smooth(l(:,I));
end
size(C2);
plot(y,C2)
    % code

The error is Error using symengine DOUBLE cannot convert the input expression into a double array.

Error in sym/double (line 613) Xstr = mupadmex('symobj::double', S.s, 0);

Error in dennInf (line 63) g=double(u);