# (ASAP)why symsum can not calculation?????

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순일 on 20 Sep 2023
Commented: Star Strider on 20 Sep 2023
t = (-2:0.5:2);
a=1;
x1=1/2 + symsum((1/2)*(sinc(a/2))*cos(2*pi*a*t)/4,a,1,inf);
plot(t,x1) Star Strider on 20 Sep 2023
It cannot be calcualted because you are not using symbolic calculations.
Perhaps this —
syms a t
% t = sym(-2:0.5:2);
% a=1;
x1(t) = 1/2 + symsum((1/2)*(sinc(a/2))*cos(2*pi*a*t/4),a,1,inf);
x1 = simplify(x1, 500)
x1(t) = Check = vpa(x1(-2:0.5:2))
Check = figure
fplot(x1, [-2 2])
grid
axis([-3 3 0 1]) Warning: Error updating FunctionLine.

The following error was reported evaluating the function in FunctionLine update: Unable to convert expression containing remaining symbolic function calls into double array. Argument must be expression that evaluates to number.
I corrected the ‘x1(t)’ expression to match the image.
.

Torsten on 20 Sep 2023
Edited: Torsten on 20 Sep 2023
t = -2:0.1:2;
a = 1;
N = 60;
n = (1:N).';
f = sinc(n/2).*cos(2*pi*a*n.*t/4);
s = 0.5 + sum(f,1);
plot(t,s) Dyuman Joshi on 20 Sep 2023
Different output for the original summation (1 to Inf)
And if the number of elements of t are increased, the code does not run in the time limit here.
t = -2:2;
syms a
x1 = 1/2 + symsum((1/2)*(sinc(a/2))*cos(2*pi*a*t)/4,a,1,Inf);
plot(t,x1) ### Categories

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