how to join points on MATLAB plot

Hello, I cannot join the points with smooth line. What I get is just scattered points on the plot. What should I do to join them ? Please let me know. See below my program:

m=50;
c=2*10^3; 
k=2*10^7;
%D=0.050; %D=50 mm workpiece diameter
%N=10;
Wn=sqrt(k/m);
Kc=3.5*10^8;
%%Ksp=1.4*10^13;
%lw=0.0005; %lw=0.01 mm to consider almost fresh tool. Previously it was 0.5 mm.
b=0.005; %Taking initial value of b=5 mm.
v=1.784; %v=pi*D*N/60; % %Was 1.784 mean value;
zeta=c/sqrt(4*k*m);
n=0:8;
w= input('Enter the value of chatter frequency at natural frequency in rad/sec:');
%Calculations
for w=w:1:1000
      for n=1:1:9
         R(w)=((Wn^2)-w^2)^2+(2*zeta*Wn)^2*w^2;
         G(w)=((Wn)^2-w^2)/R(w);
         H(w)=-(2*zeta*Wn*w)/R(w);
         b_lim(w)=-1000/(2*Kc*G(w));
         %Finding Phase angle using formulas of Altintas book 
         if (G(w)>0 && H(w)<0)
             Psi(w)=-atan(mod(H(w),G(w)))*(180/pi);
         elseif (G(w)<0 && H(w)<0)
             Psi(w)=(-pi+atan(mod(H(w),G(w))))*(180/pi);
         elseif (G(w)<0 && H(w)>0)
             Psi(w)=(-pi-atan(mod(H(w),G(w))))*(180/pi);
         elseif (G(w)>0 && H(w)>0)
             Psi(w)=(-2*pi+atan(mod(H(w),G(w))))*(180/pi);
         end    
         Theta(w)=(3*pi+2*Psi(w))*(pi/180);
         T(n,w)=(2*n*pi+Theta(w))/w;
         N(n,w)=60/(T(n,w));
         %v=(pi*D*N(n,w))/60;
         %plotting
         hold on;
         plot(N(n,w),b_lim(w),'-'); 
         %hold off;
         xlabel ('N in rpm');
         ylabel ('b-lim in mm');
         title ('Plot of b-lim vs N');
         grid on; 
      end
end

[David Young]

Please use the "{} Code" button to format your code in your question. (Edit your question to do this, don't make an answer or comment.) Without line breaks, it's hard to read your code.

[Jan]

@MILIND: Please follow David's advice. Simply open your question for editing, mark the code with the mouse and press the "{} Code" key. It takes just a second for you, but it saves a lot of time for a lot of contributors, who want to assist you.

[MILIND]

I am putting my code again, can you help me getting a smoother plot with all scattered points connected?

%%

m=50;

c=2*10^3;

k=2*10^7;

%D=0.050; %D=50 mm workpiece diameter

%N=10;

Wn=sqrt(k/m);

Kc=3.5*10^8;

%%Ksp=1.4*10^13;

%lw=0.0005; %lw=0.01 mm to consider almost fresh tool. Previously it was 0.5 mm.

b=0.005; %Taking initial value of b=5 mm.

v=1.784; %v=pi*D*N/60; % %Was 1.784 mean value;

zeta=c/sqrt(4*k*m);

n=0:8;

w= input('Enter the value of chatter frequency at natural frequency in rad/sec:');

%Calculations

for w=w:1:1000

for n=1:1:9

R(w)=((Wn^2)-w^2)^2+(2*zeta*Wn)^2*w^2;

G(w)=((Wn)^2-w^2)/R(w);

H(w)=-(2*zeta*Wn*w)/R(w);

b_lim(w)=-1000/(2*Kc*G(w));

%Finding Phase angle using formulas of Altintas book

if (G(w)>0 && H(w)<0)

Psi(w)=-atan(mod(H(w),G(w)))*(180/pi);

elseif (G(w)<0 && H(w)<0)

Psi(w)=(-pi+atan(mod(H(w),G(w))))*(180/pi);

elseif (G(w)<0 && H(w)>0)

Psi(w)=(-pi-atan(mod(H(w),G(w))))*(180/pi);

elseif (G(w)>0 && H(w)>0)

Psi(w)=(-2*pi+atan(mod(H(w),G(w))))*(180/pi);

end

Theta(w)=(3*pi+2*Psi(w))*(pi/180);

T(n,w)=(2*n*pi+Theta(w))/w;

N(n,w)=60/(T(n,w));

%v=(pi*D*N(n,w))/60;

%plotting

hold on;

plot(N(n,w),b_lim(w),'-');

%hold off;

xlabel ('N in rpm');

ylabel ('b-lim in mm');

title ('Plot of b-lim vs N');

grid on;

end

end

%%

Answer 1

[Laura Proctor]

I've gone through and vectorized your code (taken out the for loops); this will help it to run faster. The plot command now joins the points with lines.

m=50; 
c=2*10^3; 
k=2*10^7; 

Wn=sqrt(k/m); 
Kc=3.5*10^8; 

b=0.005; %Taking initial value of b=5 mm. 
v=1.784; %v=pi*D*N/60; % %Was 1.784 mean value; 
zeta=c/sqrt(4*k*m); 
n=0:8; 
w= input('Enter the value of chatter frequency at natural frequency in rad/sec:'); 
w_vec = w:1000;
R = (Wn^2 - w_vec.^2).^2 + (2*zeta*Wn)^2 * w_vec.^2;
G = (Wn^2 - w_vec.^2).^2./R;
H = -(2*zeta*Wn*w_vec)./R;
b_lim = -1000./(2*Kc*G);
Psi = -atan(mod(H,G))*180/pi;
Psi(G<0&H<0) = -180-Psi(G<0&H<0);
Psi(G<0&H>0) = -180+Psi(G<0&H>0);
Psi(G>0&H>0) = -360-Psi(G>0&H>0);
Theta = (3*pi+2*Psi)*pi/180;
n = (1:9)';
T = (2*n*ones(1,51)*pi+ones(9,1)*Theta)./(ones(9,1)*w_vec);
N = 60./T;

plot(N,b_lim,'.-');
xlabel ('N in rpm'); 
ylabel ('b-lim in mm'); 
title ('Plot of b-lim vs N'); 
grid on;

[MILIND]

Great effort ! But I am having an error at Line 22:

??? Error using ==> plus

Matrix dimensions must agree.

Error in ==> MATLABHelp at 22

T = (2*n*ones(1,51)*pi+ones(9,1)*Theta)./(ones(9,1)*w_vec);

can you please fix the above problem ?

Please also note that the 'input chatter frequency' is to be given 633....Thanks....

[MILIND]

Please help me solve the error coming at line 22: T = (2*n*ones(1,51)*pi+ones(9,1)*Theta)./(ones(9,1)*w_vec);

Thanks & Regards, Milind

Answer 2

[MILIND]

Please help me solve the error coming at line 22: T = (2*n*ones(1,51)*pi+ones(9,1)*Theta)./(ones(9,1)*w_vec);

Thanks & Regards, Milind