How do I put a summation equation in matlab?

Hi people, I need to plot the graph of f(x)= -4*(pi)^2 + the summation from n=1 (sin(n*x)*(-1)^n) / n for different values of n. I am fine plotting the graphs but I cant get the summation to work. Can anyone help?

Answer 1

[Walter Roberson]

n = 1 : 50;
sum( (sin(n*x).*(-1).^n) ./ n )

Answer 2

[Star Strider]

I’m not certain about the summation you want to do, but the cumsum function is likely worth considering.

One possibility:

x = 0.5;                                                % Scalar ‘x’
n = 1:10;
f = -4*(pi)^2 + cumsum( (sin(n*x).*(-1).^n) ./ n);

figure(1)
plot(n, f)
grid

Answer 3

[Sam Sherman]

SSEQ = (symsum(((deflectiontest)-(yq.^(2))) .^ (1 ./ 2),x,1,n)) ./ (n);

[Sam Sherman]

wtf

[Walter Roberson]

The first parameter of the symsum is the expression to be summed. The second parameter is the variable of summation. The expression looks to be independent of the variable of summation, so it looks like the result would be the first parameter times the span of the third to fourth parameter, so (n-1)+1 = n