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# Undefined function 'conv2' for input arguments of type 'sym'.

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Fatma Abdullah on 16 Jun 2017
Answered: John D'Errico on 16 Jun 2017
im trying to implement the function in the attached image but i get an error at the convolution step saying "Undefined function 'conv2' for input arguments of type 'sym'." and my code as follows :
if true
clc;
close all;
M=8;
N=32;
K=14;
c=2;
p=1;
i=13;
s=1;
syms pfa1 i T
eqn = (symsum(nchoosek(M,i)*(pfa1)^(i)*(1-pfa1)^(M-i), i, s, M)==10^(-6));
solve(eqn,pfa1);
result=solve(eqn,pfa1);
result=double(result);
result=result( result<1 & result>0 & abs(imag(result))<2*eps );
e=result
f_t=p^(c/2).*(c/2)*t.^((c/2)-1).*exp(-(t/p).^(c/2))
F_t=1-exp(-(t/p).^(c/2));
fk_t=K*nchoosek(N/2,K).*(1-F_t).^(N/2-K).*(F_t).^(K-1).*f_t
Fk_t=symsum(nchoosek(N/2,i).*(1-F_t).^(N/2-i).*(F_t).^(i), i, K, N/2)
%fz_t=2.*fk_t.*Fk_t
fz_t=conv(fk_t,fk_t)
q=fz_t.* exp(-(T*t/p).^(c/2))
fun = @(t) q
o=integral(q,0 ,Inf)
%eqn=q==e;
%T=solve(eqn, T,'Real',true)
end
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### Accepted Answer

John D'Errico on 16 Jun 2017
But conv2 is not defined for symbolic input. It was not written for that purpose. Just wanting software to do what you want is rarely going to work. I suppose that is one reason why they have documentation. :)
A convolution is just an integral. You will need to write as such, although the desired integral may or may not have a symbolic solution.
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