MATLAB: How do you separate time data from signal data, plot the signal, followed by the removal of the trend without using the inbuilt ‘detrend’ function

Question

%%. Load a signal_txt in Matlab using the importdata function. I then need to separate the time information from the signal information and plot the signal. I finally need to remove the trend without using the ‘detrend’ function.

%Task 1a

%%Heres my script code

t = signal1(:,1); %Load time data into variable t

a = signal1(:,3); %Load amplitude data into variable a

plot(t,a); %Plot time against amplitude

%%Heres my test code

x = 0:pi/100:2*pi;

y = sin(x);

plot(x,y)

Answer 1

well .... how about removing the mean to begin with?

plot(t, a - mean(a));