Generate a Valid Trading Signal based on Simple Moving Average

I am trying to generate a LONG Trading Signal based on Simple Moving Average(SMA) (using CLOSE prices) using the following rule:

LONG Signal:

close(today) > SMA(today) & close(yesterday) < SMA(today)

Both above statements must be satisfied in order to generate a valid trading signal.

I have attached a picture in which there is a green arrow. That is the point where I should be able to generate a trading signal. Purple line is a 100 days SMA.

The code I am using is as follows:

signal = zeros(numel(close),1);

for i = 2:numel(close)
    signal = close(i-1) < sma100 & close > sma100;
end

The above code does create a logical vector but all items are 0(false).

Any help to remedy the above situation would be of great help.

Thank you.