How to use SUM of Series in Matlab with .txt files?

Hi everyone!

I have 2 files with 2 cols each one( time vs Voltage or X vs Y), I try to calculate the following series but the result is always Zero (0) , What is the mistake ?

x(n) is the input vector signal

x´(n) is the output vector signal

CODE:

ECG=csvread('ecgfile1.txt');%INPUT SIGNAL
t1 = ECG(:, 1);%TIME COL 100000X1 double DATA
v1 = ECG(:, 2);%VOLTAGE COL

Prom=csvread('ecgfile2.txt');%OUTPUT SIGNAL
t2 = Prom(:, 1); %T2 100000x1double DATA
v2 = Prom(:, 2);

N=length(t1);% 
 for n=1:N
 	PRD=(sqrt( ( (t1(n)-mean(t2(n))).^2) ./ (t1(n).^2) ))*100;
end

Answer 1

[Walter Roberson]

num = 0;
denom = 0;
for n=1:N
   num = num + (v1(n) - v2(n)).^2;
   denom = denom + v1(n).^2;
end
PRD = sqrt(num ./ denom) .* 100;

Or in vectorized form:

PRD = sqrt( sum( (v1-v2).^2 ) ./ sum(v1.^2) ) .* 100;