[beginner] How do you plot two vectors of diffrent length?

Hi,

How do you go about to plot two vectors of diffent lengths in Matlab? One of my homework assignments is to great a plot graph using these two vectors:

x1 = [1 2 3 4 5 6]

y1 = [3,5 4,8 7,1 9,1 10,5 13,2]

However, this seems impossible due to the nature of the plot function, where it demands vectors to be of same length. I tried plot(x1, y1) and that didn't work. We haven't gotten anymore information than this :(

Maybe the teacher inserted a comma when it should've been a decimal point inside vector y1? He's Swedish, so maybe that's why.

Answer 1

[Dave B]

At some level the question is what you expect from the plot.

When I look at your y1 vector, I notice that it's got an odd arrangement of commas and spaces. I wondered if maybe it was intending to make a 2x6 or 6x2 matrix, which would make a lot of sense to plot against the numbers 1 to 6.

x1 = [1 2 3 4 5 6];
y1 = [3 5;4 8;7 1;9 1;10 5;13 2]; 
plot(x1,y1)

More generally, to answer the title, you can plot two different length vectors as follows:

y1 = rand(1,5);
y2 = randn(1,7);
plot(y1)
hold on
plot(y2)

[Emanuel Strid]

Thank you so much! A matrix makes much more sense! I guess my teacher incorrectly arranged the y1 vector with commas. I was just perplexed as he had never mentioned a syntax like that

[Dave B]

Happy to help, sometimes writing code involves a certain amount of mind-reading.

But just to be clear, the semicolons are the really critical bit, commas and spaces are the same when specifying a matrix (but I like the way it looks without the commas:

y1 = [3 5;4 8;7 1;9 1;10 5;13 2]; 
y2 = [3,5;4,8;7,1;9,1;10,5;13,2]; 
isequal(y1,y2)

ans = logical
   1

Answer 2

[Steven Lord]

I believe your suspicion about whether the commas should be periods is correct. MATLAB uses the convention that the decimal separator is the period, but another convention is to use a comma.

x1 =  [1 2 3 4 5 6];
y1 = [3.5 4.8 7.1 9.1 10.5 13.2];
plot(x1, y1)