how to perform summation operation

i have an equation

X=1/K summation i=i to k *(Ai ^2) where k=10...

please help

Answer 1

[Walter Roberson]

A1k = A(1:k);
A1k2 = A1k .^ 2;
sumA1k2 = sum(A1k2);
avgA1k2 = sumA1k2 / k;

In some situations the calculation could be reduced to

mean(A.^2)

By the way: if you just happen to be doing a variance or standard deviation calculation, then the division would normally be by k-1 rather than by k. See http://en.wikipedia.org/wiki/Bessel%27s_correction

[kash]

walter what is A

my values should be as A1,A2.....A10

A1is 1st value ,,,,so on

[Walter Roberson]

If your data is in separate variables, then Don't Do That.

http://matlab.wikia.com/wiki/FAQ#How_can_I_create_variables_A1.2C_A2.2C....2CA10_in_a_loop.3F

[kash]

A = zeros(1,10); % Not necessary, just much faster

for i=1:10

A(i) = % some equation

end

what equation i must write in A(i)

[Walter Roberson]

A = [A1, A2, A3, A4, A5, A6, A7, A8, A9, A10];

Now proceed with the code I showed above.