MATLAB: How could I use if function to update the newest maximum value

Question

Hi all,

I am going to use photodiode to monitor my laser and capture the max power during the machine is operating.

So, I write the code to generate similar signal and want to build a tool for me can always update the maximum value in the real time.

I have thought about using "if" to update the max value when the latest one is higher but not sure how to implemente it?

Here is my code below, I used rand() to produce random amplitude signal:

fs = 50000; % 50 kHz frequency
Ts = 1/fs*10^9; % sample rate in neno seconds
t = 1:Ts;
pulse = t<=5;
rand_amp = rand(10,1);
sig = pulse.*rand_amp;
sig = reshape(sig', [], 1);
t_total = 1:numel(sig);
plot(t_total, sig);
%find the maximum
maxPulse= max(sig);
xlabel('Time (ns)');
ylabel('Amplitude');

Answer 1

Try this

fs = 50000; % 50 kHz frequency
Ts = 1/fs*10^9; % sample rate in neno seconds
t = 1:Ts;
pulse = t<=5;
rand_amp = rand(10,1);
sig = pulse.*rand_amp;
sig = reshape(sig', [], 1);
max_val = zeros(size(sig)); % save maximum value at each time step;
max_val(1) = sig(1); % first maximum value is the first sample of sig
for i=2:numel(max_val)
    if sig(i) > max_val(i-1)
        max_val(i) = sig(i);
    else
        max_val(i) = max_val(i-1);
    end
end
t_total = 1:numel(sig);
figure;
plot(t_total, sig);
xlabel('Time (ns)');
ylabel('Amplitude');
figure;
plot(t_total, max_val);
xlabel('Time (ns)');
ylabel('Amplitude');