I have some point and one line.

I have some point and one line.

my points are in (x,y) written in under

X = ...
    [   1   1
    1   3
    1   5
    1   7
    1   9
    1   11
    1   13
    1   15
    1   17
    3   1
    3   3
    3   5
    3   7
    3   9
    3   11
    3   13
    3   15
    3   17
    5   1
    5   3
    5   5
    5   7
    5   9
    5   11
    5   13
    5   15
    5   17
    7   1
    7   3
    7   5
    7   7
    7   9
    7   11
    7   13
    7   15
    7   17
    9   1
    9   3
    9   5
    9   7
    9   9
    9   11
    9   13
    9   15
    9   17
    11  1
    11  3
    11  5
    11  7
    11  9
    11  11
    11  13
    11  15
    11  17
    13  1
    13  3
    13  5
    13  7
    13  9
    13  11
    13  13
    13  15
    13  17
    15  1
    15  3
    15  5
    15  7
    15  9
    15  11
    15  13
    15  15
    15  17
    17  1
    17  3
    17  5
    17  7
    17  9
    17  11
    17  13
    17  15
    17  17];

and my line is

 r=[0 10 15 20 30];
 t=[10 10 15 10 10];
f= line(r,t)

how can i find wich points are under the line??

please help me its emergency

[David Welling]

Since there is only a small number of cases, you could do it by hand, especially since the line is so simple.

plot the line and the points and you will see it easily.

for a more general case using arbitrary points and lines, I suggest interpolating to find the y value of the line for a given x of the point, and then comparing y_line and y_point

[Mili Kian]

these points were for example. in fact i have more than a hundread points.

Answer 1

[Ameer Hamza]

try this. X is the n*2 matrix given in your question

r=[0 10 15 20 30];
t=[10 10 15 10 10];

x = interp1(r,t, X(:,1));
mask = X(:,2) >= x;
plot(r, t, 'r', X(mask,1), X(mask,2), 'r*',  X(~mask,1), X(~mask,2), 'b*')

[Mili Kian]

Thanks alot

this is the code that i want

best regard

[Ameer Hamza]

Glad to be of help.