symbolic calculation for series

syms x t
U=zeros(5)
for k=1:5
    if mod(k,2)~=0
        U(k,1)=0
    else
        U(k,1)=(((-1)^(k-2))/factorial(k))*sym(pi);
    end
end

I want to to assign U(k,1) value in terms of pi not in numbers

Answer 1

[Wan Ji]

Hi friend,

Just define U as a symbolic array, it works in my matlab

syms x t
syms U [5,1] % I think what you need is 5-by-1 matrix
for k=1:5
    if mod(k,2)~=0
        U(k,1)=0;
    else
        U(k,1)=(((-1)^(k-2))/factorial(k))*pi;
    end
end
U

The result is

U =
 
     0
  pi/2
     0
 pi/24
     0
   

[YOGESHWARI PATEL]

Thnak you

Answer 2

[John D'Errico]

But you defined U as a double precision array! See the difference.

V = zeros(5)

V = 5×5

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Note that zeros(5) creates a 5x5 array. If you wanted a vector of length 5, then use zeros(5,1) or zeros(1,5).

But now, had you done it like this:

U = zeros(5,'sym')

U = 

whos U V

  Name      Size            Bytes  Class     Attributes

  U         5x5                 8  sym                 
  V         5x5               200  double              

So U is a symbolic array of zeros. Now when you assign elements into U, there is no problem.

U(1) = sym('pi')

U = 

[YOGESHWARI PATEL]

Thank you