hi everybody , i have a question please , if i have X=[1:10] and Y=[-5:5] and i want to have all the point of the plane (x,y) , what can i do in matlab to extract this point to use it

X=[1:10];

Y=[-5:5];

for i=1:10

for j=1:10

[Alex Mcaulley]

Please be more clear, what do you want exactly?

[Jan]

I do not understand also, what "have point of the plane" means. Extract them from what?

BY the way: -5:5 is a vector already and you do not need the square brackets. And it has 11 elements, not 10.

[mina massoud]

first i need to thank you for responding on my question ,

i try now to be more clear

1) what i need is a column vector 2x1 where the first row is x and the second row is y

2) i need to repeat it to get all the point of the plane (x,y)

for example if X=[ 1 2 3 4 5 ]

Y=[ -5 -4 -3 -2 -1 0 1 2 3 4 5]

so (1,-5) (2,-5) (3,-5)(4,-5)(5,-5)

(1,-4) (2,-4) (3,-4)(4,-4)(5,-4)

(1,-3) (2,-3) (3,-3)(4,-3)(5,-3)

and so on till ..........................................(1,5) (2,5) (3,5)(4,5)(5,5)

so i need in a cartesian coordinate all the pointi (x,y) to use it in a certain iteration

so every cycle i need to extract a point (x,y) that is a column vector 2x1 where the first row is the point x and the second row is the point y to use it in a certain iteration

thank u very much

Answer 1

[James Tursa]

Does this do what you want?

[x,y] = meshgrid(X,Y);
result = [x(:),y(:)];

Then iterate over the rows of result.

Or you can just use your double for loop, and have

for i=1:numel(X)
    for j=1:numel(Y)
        point = [X(i),Y(j)];
        etc.

[mina massoud]

thank u very much , u r the best

[mina massoud]

please can u tell me how can i save the result in a matrix because he save only the last resutl (5,5)

x=[1 2 3 4 5 ];

y=-5:5;

tgt=zeros(55,2);

for i=1:length(x)

for j=1:length(y)

tgt=[x(i),y(j)]

end

end

[James Tursa]

Save what in a matrix? Just the points? E.g.,

tgt = zeros(numel(x)*numel(y),2);
k = 0;
    :
    % then inside the loop
    k = k + 1;
    tgt(k,:) = [x(i),y(j)];

[mina massoud]

i tried this code but it didnt work

clear all  
clc 
intx=10;
inty=10;
D_x=3000;
D_y=1000;
x=[0:intx:D_x];
y=[-D_y/2:inty:D_y/2];
k=0
TgT=zeros(length(x),length(y))
for i=1:length(x)
    for j=1:length(y)
        k=k+1
        TgT(k,:)=[x(i),y(j)]
      end 
end 

[James Tursa]

You didn't pre-allocate TgT to the dimensions I specified. You have this:

TgT=zeros(length(x),length(y))

But I have this:

tgt = zeros(numel(x)*numel(y),2);

[Jan]

@mina: "it didnt work" is not useful to explain a problem. Do you get an error message (than post a complete copy) or do the result differ from your expectation (then explain both).

clear all; clc is called "cargo cult programming": It does not help to solve any problem. All it does is to waste processing time here.

A simpler method instead of the loops:

x   = 0:intx:D_x;         % No need for brackets
y   = -D_y/2:inty:D_y/2;  % x and y are vectors already
nx  = numel(x);
ny  = numel(y);
TgT = [replem(x.', ny, 1), repmat(y.', nx, 1)];

Answer 2

[madhan ravi]

I am not sure I fully understand but see if it does what you want

[x,y]=ndgrid(X,Y);
[x(:) y(:)] % after this it’s just matrix manipulation