Plotting iterations vs error for false position method

I am trying to plot the error per iteration, the graph keeps coming back blank.

clear all
clear vars
p = 1.23;
Q = input('Flow ');
v = (4*Q)/(pi*0.5^2);
d = 0.5;
u= 1.79*10^(-5);
re = (p*v*d)/u;
xl=.00001;
xu=1;
imax=100;
f =@(x) ((4*log10((re)*sqrt(x)))-.4)-(1/(sqrt(x)));
icurrent=0;
error = 100;
xr=xu-((f(xu)*(xl-xu))/(f(xl)-f(xu)));
disp('    i           xl              xu            xr            xro              error')
while icurrent<imax
    xrOLD=xr;
    icurrent=icurrent+1;
    f(xl);
    f(xu);
    xr=xu-((f(xu)*(xl-xu))/(f(xl)-f(xu)));
    test=f(xr)*f(xl);
    if icurrent > 1
        error = abs(((xr-xrOLD)/xr)*100);
    end
    if icurrent <= 2
        error = abs(((xr-xrOLD)/xr)*100);
    end
    fprintf(1,'\t%g\t%12g\t%12g\t%12g\t%12g\t%12g\n',icurrent,xl,xu,xr,xrOLD,error)
    if test>0
    xl=xr;
    end
    if test<0
    xu=xr;
    end
    hold on 
    plot(icurrent,error)
end

Answer 1

[KALYAN ACHARJYA]

Both icurrent and error are scalars, how can you expect a graph. Try to make vector, so that you can plot.

Here I am trying to show you how vcan you generate plot parameters, please ensure that I have just check the code to generate plot only (Please check the data and changes as per your requirements)

p = 1.23;
Q = input('Flow ');
v = (4*Q)/(pi*0.5^2);
d = 0.5;
u= 1.79*10^(-5);
re = (p*v*d)/u;
xl=.00001;
xu=1;
imax=100;
f =@(x) ((4*log10((re)*sqrt(x)))-.4)-(1/(sqrt(x)));
icurrent=[];
error=[];
icurrent(1)=0;
error(1)= 100;
i=1;
xr=xu-((f(xu)*(xl-xu))/(f(xl)-f(xu)));
disp('    i           xl              xu            xr            xro              error')
while icurrent(i)<imax
    xrOLD=xr;
    icurrent(i+1)=icurrent(i)+1;
    f(xl);
    f(xu);
    xr=xu-((f(xu)*(xl-xu))/(f(xl)-f(xu)));
    test=f(xr)*f(xl);
    if icurrent(i) > 1
        error(i+1)= abs(((xr-xrOLD)/xr)*100);
    end
    if icurrent(i) <= 2
        error(i+1)= abs(((xr-xrOLD)/xr)*100);
    end
    fprintf(1,'\t%g\t%12g\t%12g\t%12g\t%12g\t%12g\n',icurrent(i+1),xl,xu,xr,xrOLD,error(i+1))
    if test>0
    xl=xr;
    end
    if test<0
    xu=xr;
    end
    hold on 
    i=i+1;
end
plot(icurrent,error);

Hope it Helps!