Multiple plots in one iterative script

I'm trying to plot two graphs that plot the iterations and respective errors. I'm not sure what I'm doing wrong. Thanks in advance

function BisectMeth(xL, xU, es, itermax)
f = @(x)exp(-x)-x;
xR = xU;
fL = f(xL);
for iter = [1:itermax]
    xRold = xR;
    xR = (xL +xU)/2;
    fR = f(xR);
    if xR ~= 0
        ea = abs((xR-xRold)/xR)*100;
    end
    check = fL*fR;
    if check <0
        xU = xR;
      
    else
        if check > 0
            xL = xR;
            fL = fR;
        else 
            ea = 0;
        end
   
    end
    if ea < es 
        break
    end
    if iter == itermax && ea > es
        disp('Max # of iterations reached before acheiving prescribes tolerance')
    end
    iter = [0:itermax]
 AppErr = (xR*ea)/100;
 TrueErr = 0.56714329 - xR;
 
 figure(1);
 plot(iter,TrueErr);
 xlabel('Number of Iterations');
 ylabel('True Error');
 
 figure(2);
 plot(iter, AppErr);
 xlabel('Number of Iterations');
 ylabel('Approximate Error');
end

fprintf('Root is %f\n', xR)
fprintf('Approximate error is %f\n',AppErr)
fprintf('True error is %f\n', TrueErr)
end

Answer 1

[Vishesh]

• Store the values of "AppErr" and "TrueErr" of each iteration together.
• Plot the graph outside of the iteration.
• You can use this code for the reference.

function BisectMeth(xL, xU, es, itermax)
f = @(x)exp(-x)-x;
xR = xU;
fL = f(xL);
AppErr=[];
TrueErr=[];
for iter = [1:itermax]
    xRold = xR;
    xR = (xL +xU)/2;
    fR = f(xR);
    if xR ~= 0
        ea = abs((xR-xRold)/xR)*100;
    end
    check = fL*fR;
    if check <0
        xU = xR;
      
    else
        if check > 0
            xL = xR;
            fL = fR;
        else 
            ea = 0;
        end
   
    end
    if ea < es 
        break
    end
    if iter == itermax && ea > es
        disp('Max # of iterations reached before acheiving prescribes tolerance')
    end
    
 AppErr = [AppErr (xR*ea)/100];
 TrueErr = [TrueErr 0.56714329 - xR];
 
 
end
 iter=1:itermax;
 figure(1);
 plot(iter,TrueErr);
 disp(iter);
 disp(TrueErr);
 xlabel('Number of Iterations');
 ylabel('True Error');
 
 figure(2);
 plot(iter, AppErr);
 xlabel('Number of Iterations');
 ylabel('Approximate Error');
fprintf('Root is %f\n', xR)
fprintf('Approximate error is %f\n',AppErr)
fprintf('True error is %f\n', TrueErr)
end