finding a sum of a vector without using the sum(x) function

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SonOfAFather
SonOfAFather 2012-9-12
I can make my program give the correct answer using the sum(x) function, but i can't use the sum(x) function. is there a way to use either a for or while loop to accomplish the same thing. my present code is:
clc;
clear all;
close all;
w = [1,1.2,.8,1];
x = [75, 80, 65, 78];
wa = 75;
for i = 1:1:length(x);
wa(i) = x(i)*w(i);
end
sum(wa(1:i)./i)
this yeilds the 75.25 answer that i should get. is there some simple that will fix the sum(wa(1:i)./i) I know that i can use the finite fix of wa(1)+wa(2)+...+wa(i), but i need it to work for any number of indexis of wa. as sum(wa(1:i)) does.

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采纳的回答

Sean de Wolski
Sean de Wolski 2012-9-12
编辑：Sean de Wolski 2012-9-12
Okay code golf:
w*x'/numel(x)

更多回答（1 个）

Matt Fig
Matt Fig 2012-9-12
If you don't need all of the wa, you should just do a running sum.
w = [1,1.2,.8,1];
x = [75, 80, 65, 78];
wa = 0;
for ii = 1:1:length(x);
wa = wa + x(ii)*w(ii);
end
wa/ii

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