Error trying to draw a spline

 Hi,

I am trying to dray the blue line on the image below on matlab based on the geometry of the t-joint. I use coordinate iteration and spline fct to do so. I don't know why but I can't get it to work properly. Can you enlight me ?

Thanks,

 clear all;
  clc;
  %TJoint Winding w/o radius
  %The idea is to experiment with matlab 

%Obtains the values 
D = 'What is the diameter of the t joint? ';
D = input(D);

l1 = 'What is the length 1 of the t joint? ';
l1 = input(l1);

l2 = 'What is the length 2 of the t joint? ';
l2 = input(l2);

w = 'What is the width of the carbon fiber used? ';
w = input(w);

'Thank you, we are now processing the Filament winding of your T-Joint. Please wait ';

%Defining Graph size
x = -D/2:((D/2)+l2);
y = -l1/2 :l1/2;
z = -D/2: D/2;

%Variable Definition
r = D/2;

%Winding step one

for y=-r-l2:0.01:0;
    x = (-(r+l2)/r);
    z = sqrt((r.^2)-(x.^2));
    xyz = [x ; y ; z];
    %can be erased to remove points
    hold on;
    fnplt(cscvn(xyz(:,[1:end 1])),'r',2);
    end

      %Axis Labeling
  xlabel('X Axis','FontSize',14);
  ylabel('Y Axis','FontSize',14);
  zlabel('Z Axis','FontSize',14);
  title('Tjoint winding w/o radii','FontSize',14);

[Walter Roberson]

Are you encountering an error message?

[Cedrick Levesque-Baker]

Hi Walter, it says that imaginary number have been discard, which should not happen and the output is straight spline

this line seems to be the error : z = sqrt((r.^2)-(x.^2));

Answer 1

[Cedrick Levesque-Baker]

I finally found my mistakes and they were pretty obvious, I was just not paying attention enough. Here it is if it can be useful to someone.

clear all;
clc;
%TJoint Winding w/o radius
%The idea is to experiment with matlab 

%Obtains the values 
D = 'What is the diameter of the t joint? ';
D = input(D);

l1 = 'What is the length 1 of the t joint? ';
l1 = input(l1);

l2 = 'What is the length 2 of the t joint? ';
l2 = input(l2);

w = 'What is the width of the carbon fiber used? ';
w = input(w);

'Thank you, we are now processing the Filament winding of your T-Joint. Please wait ';

%Defining Graph size
x = -l1/2 :l1/2;
y = -D/2:((D/2)+l2);
z = -D/2: D/2;

%Variable Definition
r = D/2;

%Winding step one

for y=-r-l2:0.01:0;
    x = (-r/(r+l2))*y ;
    z = sqrt(r.^2-x.^2);
    xyz = [x ; y ; z];
    %can be erased to remove points
    fnplt(cscvn(xyz(:,[1:end 1])),'r',2);
    hold on;
    end

      %Axis Labeling
  xlabel('X Axis','FontSize',14);
  ylabel('Y Axis','FontSize',14);
  zlabel('Z Axis','FontSize',14);
  title('Tjoint winding w/o radii','FontSize',14);