Matlab for Beginners, Plotting from a matrix!

Hello, this is building from last post, I am dumb in matlab, and greatly appreciate your help. It should not be hard if I was smart enough.

23431 20757 21860 47209

23760 21059 22144 47781

25986 22832 23719 50101

This is a matrix, in the first picture, and the numbers above are the first three lines. Please provide code to divide the first three numbers, by the fourth number on each line respectively. Then, you will get three values for each line, simply then plot the three values to X, Y, X dimensions respectively. Result should be graph.

Thank you so much!

I admit I am new and very dumb in matlab.

Answer 1

[David Hill]

I assumed you wanted 3d graph (X,Y,Z).

M=%your maxtrix
m=M(:,1:3).*repmat(M(:,4),1,3);
plot3(m(:,1),m(:,2),m(:,3))

[David Hill]

M=%your maxtrix
m=M(:,1:3)./repmat(M(:,4),1,3);%divide not multiply
plot3(m(:,1),m(:,2),m(:,3))

[Justin Jiang]

thanks for your help,

can you briefly explain the second line?

what does M(: ,1:3) mean? particularly the (:, not sure

what does repmat mean ? is this defining a new matrix

what does M(:,4) mean? does it mean the four line of the matrix?

what does ,1,3) mean? im not sure what this mean

[David Hill]

M(:,1:3) is all rows and columns 1 through 3 of matrix M.

The repmat() function repeats matrixes or vectors to create a new matrix. You should look at the function yourself in the document section of Matlab. repmat(M(:,4),1,3) makes a matrix of column 4 of M repeated 3 times.