Edit: I first thought you wanted to store the values of 'i' when the conditions are true. So, I would use a vector for that. If you don't want that, just sum(tricond) in the end. Also, changed loop from 1
In your code you save 'i' to a file repeatedly, which is unnecessary. File access is slow. Always store data in variables like matrices of vectors first, then after the loop, store the variable in a file.
I also would like to work from "today" to "yesterday" by stepping in the variables o and c from i=1 to numElems-2.
After everything is stored in tricond I save the results in a file. here is my take on it:
str = urlread('http://ichart.yahoo.com/table.csv?s=AMZN&a=0&b=1&c=2008&d=0&e=31&n=2014&g=d&ignore=.csv');
i = 0;
[dates, o, h, l, c] = dataread('string',str,'%s%f%f%f%f%*f%*f','delimiter',',','headerlines',1);
dates = datenum(dates);
numElems = length(dates);
tricond = zeros(numElems, 1, 'uint8'); %binary vector
fd = fopen('output.txt','w');
for i=1:numElems-2
%Say we think of today as 'i', the yesterday will be i+1
%The condition can be phrased as:
%"Opening price today is larger than open pice for yesterday and...
%the closing price for today is larger than yesterday and...
%the opening price for day before yesterday is smaller than the closing
%price for that day"
if o(i) < o(i+1) & c(i) > c(i+1) & o(i+2) < c(i+2)
tricond(i) = 1;
end
end
fprintf(fd, '% g\n', tricond); %save the integers
