Error in figure (2)

R=10; %% radius of workpiece

f=0.5; %% feed rate in mm/min

s=50; %% spindle speed in rpm

N=100; %% no of points in one revoultions

a=f/(s*N);

Ax=2; %% amptitude in x-direction

Ay=2; %% amptitude in y-direction

lx=2.5; %% wavelenght in x-direction

ly=2.5; %% wavelenght in y-direction

n=((R*s*N)/f)+1; %% total number of points for given function

t=0.5; %% tool nose radius

Pi = (pi); %% storing the value of pi

for i=1:n

r(i)=(R-((i-1)*a)); %% calculation of radial distance

theta(i)= ((i-1)*(2*Pi/N)); %% calculation of theta

x(i)=(r(i)*cos(theta(i))); %% converting polar to cartesian for x

y(i)=(r(i)*sin(theta(i))); %% converting polar to cartesian for y

Z(i)=((Ax*cos(2*Pi*x(i)/lx))+(Ay*cos(2*Pi*y(i)/ly))); %% calcualtion of height for given function

end

figure(1)

T=delaunayTriangulation(x(:),y(:));

trisurf(T.ConnectivityList,x(:),y(:),Z(:),'EdgeColor','none','FaceAlpha',0.6);

view(-80,75) %% 3d surface plot

for j=1:n-1

u(j) = r(j);

p(j) = Z(j);

u(j+1) = r(j+1);

p(j+1) = Z(j+1);

m(j) =((p(j+1) - p(j))./(u(j+1)-u(j)));

newth(j+1) = atan(-m(j));

G(j)=r(j)-(t*sin(newth(j+1)));

J(j)=G(j).*cos(newth(j+1)); %% converting polar to cartesian for x

K(j)=G(j).*sin(newth(j+1)); %% converting polar to cartesian for y

H(j)= Z(j)+(t*cos(newth(j+1)))-t;

end

figure(2)

T=delaunayTriangulation(J(:),K(:));

trisurf(T.ConnectivityList,J(:),K(:),H(:),'EdgeColor','none','FaceAlpha',0.6);

view(-80,75)

For figure (1) , three part i.e. part-I-III equation has been used to plot. I am able to generate the figure (1) plot with given equation successfully. Part -IV equation shows the some modification of part-I and part-II equations and figure (2) plot should be according to this modification. Figure (2) should be somewhat similiar to figure (1), but i am getting totally different result. Can you please look into the code how it can be corrected??

Thank you