simple plot question (:,1)

im currently revising my matlad university course and although i understand the majority of code i strugle when it come to plotting. the main question is when to use

    plot(y(:,1),y(:,2),'r');

i cannot figure out what the difference is if i do not use (:,1) or what this means exactly?

any help much appriciated

Answer 1

[Chandra Shekhar]

Here your y is having two columns and many rows.

Here you are considering y(:,1) in x-axis and y(:,2) in y-axis in the plot.

If you use plot(y,'r'), then two column will plot in y-axis and x-axis will be some random value.

if you want more clear idea in plotting just check this different plots.

y=rand(10,2);
plot(y(:,1),'r');
plot(y(:,2),'r');
plot(y,'r');
x=1:10; % here x-axis assumed from 1 to 10
plot(x,y,'r');
plot(x,y(:,1),'r');
plot(x,y(:,2),'r');