Code display blank plot

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Omer Yaish Maman
Omer Yaish Maman on 11 May 2020
Commented: Image Analyst on 11 May 2020
My code is calculating a non-linear equation system with Newton-Rhapson method, and I'm trying to show a plot of "iterration"(i) as function of "error vector"(h1).
Maybe because i is scalar and h1 is a vector?
How can i fix the code for making a plot like i want?
syms x y z
u = (x*y)-z^3-2;
v = (x*y*z)-x^2+y^2-4;
w = exp(x)-exp(y)+cos(z)-6;
xo = 1;yo = 1;zo = 1;
k = 10;
i = 0;
a = jacobian([u;v;w],[x,y,z]);
while i<k
j=subs(a,[x,y,z],[xo,yo,zo]);
j_i=j^-1;
uo=subs(u,[x,y,z],[xo,yo,zo]);
vo=subs(v,[x,y,z],[xo,yo,zo]);
wo=subs(w,[x,y,z],[xo,yo,zo]);
sol=[xo;yo;zo]-j_i*[uo;vo;wo];
sol=double(sol);
x1=sol(1,1);
h1=j_i*[uo;vo;wo];
xo=sol(1,1);
yo=sol(2,1);
zo=sol(3,1);
i=i+1;
plot(i,h1,'r');
hold on
xlabel('Error Vector')
ylabel('Iterration')
end
X=xo;
Y=yo;
Z=zo;
X,Y,Z
  2 Comments
dpb
dpb on 11 May 2020
Probably just that a single pixel is too small to show up on the screen...try
plot(i,h1,'rx','markersize',3);
Omer Yaish Maman
Omer Yaish Maman on 11 May 2020
Thank you very musch that was helpful

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Answers (1)

Image Analyst
Image Analyst on 11 May 2020
Edited: Image Analyst on 11 May 2020
Try this:
plot(1 : length(h1), h1, 'r.', 'MarkerSize', 15);
grid on;
hold on
drawnow;
or simply
plot(h1, 'r.', 'MarkerSize', 15);
grid on;
hold on
drawnow;
  1 Comment
Image Analyst
Image Analyst on 11 May 2020
Glad changing the markersize fixed it for you.

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