point that are under line equation

i have multi sentence equation and some point like this:

0<x<5 y=6

5<x<12 y=3x+6

12<x<15 y=-3x+7

15<x<20 y=6

and my points are(x,Y)

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

how can i find which point are under the equation

Answer 1

[Michael Soskind]

Hi Mili,

There are a few ways to go about this, I think the most obvious is the one I outline below:

% Redefining columns as x and y for clarity
x = C(:,1);
y = C(:,2);

% Conditions stated in question
cond_1 = x > 0 & x < 5 & y < 6;
cond_2 = x > 5 & x < 12 & y < 3*x + 6;
cond_3 = x > 12 & x < 15 & y < -3*x + 7;
cond_4 = x > 15 & x < 20 & y < 6;

% Selecting the points matching the conditions
points_below = C(cond_1 | cond_2 | cond_3 | cond_4, 1:2)

The method above assumes the array is called C. I redefine the columns into variables. I then use conditional statements that select for points matching the conditions above. NOTE: You may want to review the conditions you have in place, as they seem a bit strange to me, and maybe not what you are intending for.

However, the above should provide you with the final set of points as shown in the array points_below. Conditional statements are very powerful in Matlab.

Best,

Michael

[Mili Kian]

thank you

yes,as you said 'Conditional statements are very powerful in Matlab.'

best regard

Answer 2

[Image Analyst]

I just answered this in your duplicate question: https://www.mathworks.com/matlabcentral/answers/518908-i-have-number-of-points-that-have-x-y-then-i-define-a-line-and-i-want-to-realize-which-points-are#comment_832507