How can I use the subplot command to plot the root estimates vs iterations and the error vs iterations

this is my code:

Use bisection method to find the root

f = @(x) x.^3 - (9)*x.^2 + 3.8197
xl = -1000
xu = 1000
xm = (xl+xu)/2
error = 20
while error > 0.001
if (f(xm).*f(xl))<0
xu=xm
xm2 = (xl+xu)/2
error = (xm2-xm)/xm2
error = abs(error)
xm = xm2
else
       xl=xm
xm2 = (xl+xu)/2
error = (xm2-xm)/xm2
error = abs(error)
xm = xm2
end
xm= (xl+xu)/2
end

the root is -0.6299 with error = 0.0757%

How can I collect the error and root estimate at each run, and use subplot command to plot 1: root estimates vs iterations and 2:error vs iterations\

thank you very much!

Answer 1

[darova]

Try this

figure
hold on
while %condition
    % some code
    subplot(2,1,1)
    plot(iter,root)
    subplot(2,1,2)
    plot(iter,error)
    iter = iter + 1;
end

[wenchong chen]

how can I collect the date for root and iter and root and error at each run?

[wenchong chen]

hold on

f = @(x) x.^3 - (9)*x.^2 + 3.8197

xl = -1000

xu = 1000

iter = 1

xm = (xl+xu)/2

error = 20

while error > 0.001

if (f(xm).*f(xl))<0

xu=xm

xm2 = (xl+xu)/2

error = (xm2-xm)/xm2

error = abs(error)

xm = xm2

else

xl=xm

xm2 = (xl+xu)/2

error = (xm2-xm)/xm2

error = abs(error)

xm = xm2

end

xm= (xl+xu)/2

subplot(2,1,1)

plot(iter,xm)

subplot(2,1,2)

plot(iter,error)

iter = iter + 1;

end

[wenchong chen]

the code runs and two subplot pops out but no plot on them, what wrong with my code?

[wenchong chen]

hold on

f = @(x) x.^3 - (9)*x.^2 + 3.8197

xl = -1000

xu = 1000

iter = 1

xm = (xl+xu)/2

error = 20

while error > 0.001

if (f(xm).*f(xl))<0

xu=xm

xm2 = (xl+xu)/2

error = (xm2-xm)/xm2

error = abs(error)

xm = xm2

else

xl=xm

xm2 = (xl+xu)/2

error = (xm2-xm)/xm2

error = abs(error)

xm = xm2

end

xm= (xl+xu)/2

subplot(2,1,1)

plot(iter,xm)

subplot(2,1,2)

plot(iter,error)

iter = iter + 1;

end