I keep getting this for my function and I don't know how to fix it -- Undefined function 'symsum' for input arguments of type 'double'.

This is what have, a pic is also attached of the problem, have to find phi values of n =5,10 and 50

 function phi = prob2_6(n)

 phi = 13/8 + symsum(((-1).^(n+1)).*factorial(2.*n+1)./factorial(n+2).*factorial(n).*((4).^(2.*n+3)),n,0,n)

 return

Answer 1

[Image Analyst]

Can you use sum() instead?

[Luke Radcliff]

sorry Im new to matlab, something like this

 phi = 13/8 + sum(((-1).^(n+1)).*factorial(2.*n+1)./factorial(n+2).*factorial(n).*((4).^(2.*n+3)),n,0,n)

cause if it is still wont work

[Image Analyst]

It doesn't know what the ,n,0,n arguments at the end are. What are those used for in symsum()? I don't have the symbolic toolbox so I don't know.

[Alex Lisichenko]

answer is

n = 0:N;

phi = 13/8 + sum(((-1).^(n+1)).*factorial(2.*n+1)./(factorial(n+2).*factorial(n).*((4).^(2.*n+3))))

Answer 2

[VBBV]

format long
N = [5 10 50]; 
Phi = prob2_6(N)  % call function by passing vector of values with range N 

Phi = 1×3

1.618034154176712 1.618033988674355 1.618033988749895

function phi = prob2_6(N)  
  
  for k = 1:length(N)
      n = 0:N(k);       
      phi(k) = 13/8+sum(((-1).^(n+1).*factorial(2.*n+1))./(factorial(n+2).*factorial(n).*(4.^(2.*n+3))));  
  end
end