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symbolic calculation for series

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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

Accepted Answer

Wan Ji
Wan Ji on 29 Aug 2021
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

More Answers (1)

John D'Errico
John D'Errico on 29 Aug 2021
Edited: John D'Errico on 29 Aug 2021
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 = 

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