# How can i save two points with lambda in a vector ?

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Jan Nabo on 18 Oct 2019
Commented: Jan Nabo on 22 Oct 2019
i have four coordinates and my formula is that i want from two points for example P1(-1|1) and P2(1|1) many points on this "connection or line". I have P3(1|-1) and P4(-1|-1)
so vector for two points is v = P1 + Lambda + (P2 -P1) for Lambda is [0:0.2:1] so i can make more points for this points and connected them.
But how can i transform this in matlab with a for-loop ?
I want only rectangle so the connection and calculation is possible for P1 and P2, P2 and P3, P3 and P4.
------------------------
index
for i =1:4
for Lambda = 0:0.25:1;
v(index) = x(i),y(i) + Lambda * ( x(i+2),y(i+2) - (x(i),y(i)))
index=index+1;
end
i tried this but i don't think that is right

Dimitris Kalogiros on 18 Oct 2019
Edited: Dimitris Kalogiros on 18 Oct 2019
Run this:
clear; clc; close all;
%input points
Points=[1 1; -1 1; -1 -1; 1 -1 ];
% make 'Points' to represent an closed line
Points=[Points; Points(1,:)];
% plot rectangular, using a loop
figure(1); hold on;
numPoints=size(Points,1);
for n=1:numPoints-1
n_start=n;
n_end= 1+n;
figure(1); plot(Points(n_start:n_end,1), Points(n_start:n_end,2),'-b*', 'linewidth', 1);
zoom on; grid on;
end
% make figure looking better
axis([min(Points(:,1))-1 max(Points(:,1))+1 min(Points(:,2))-1 max(Points(:,2))+1]);
ax=gca;
ax.XAxisLocation = 'origin';
ax.YAxisLocation = 'origin';

#### 1 Comment

Jan Nabo on 22 Oct 2019
function out = Randerzeugen(xwert,ywert,X,Y,isInside,block1,randdicke)
sz_x=size(xwert,1);
out=false(size(X));
if (~isInside == true)
Points=[xwert(:) ywert(:)];
Points=[Points;Points(1,:)];
numPoints=size(Points,1);
Lambda= 0:0.25:1;
for n=1:numPoints-1
out = out | (Points(n,1)+Lambda *( Points(n,2)-Points(n,1))) <= randdicke*2;
end
elseif (isInside == true)
block1=~block1;
for i=1:sz_x
out=out | (((X-xwert(i)).^2)+((Y-ywert(i)).^2) <= randdicke*2);
end
out= and(out,block1);
end
end
the problem is... i have to save the points from the calculation and compare it with my logical "out" you can see that in if(~isInside == true) there i want to save the points and compare it later with the logical out. it will be a 3D-Object. But how can i use my formula to calculate each points.