MATLAB: My Modified regula falsi code has the same number of iterations and error value as the regular falsi code that I made. Why is this

codefalsimodifiedregula

This is my modified regula falsi code
clear all; clear clc;
g = 9.81; %acceleration m/s^2

m = 68.1; %mass, kg

t = 20; % time, seconds

f = @(c) g*m./c.*(1-exp(-c/m*t))-93.71;
c = 2:20;
plot (c, f(c))
xlabel('c = 2:20')
ylabel('Velocity formula in terms of c')
title('Plot of velocity function with respect to c')
a = 4; b = 8;
error = 1;
mold = 1;
SF = 6;
i = 1;
F = f(a);
G = f(b);
while (1)
     m = (a*G - b*F)/(G-F);
    if F*f(m) < 0
        b = m;
        G = f(m);
        if F*f(m) > 0
            F = F/2;
        end
    else
        a = m;
        F = f(m);
        if f(a)*f(m) > 0
            G = G/2;
        end
    end
    error = abs ((m-mold)/m);
    if error < 0.5*10^-SF
        break
    end
    mold = m;
    i = i + 1; %iteration counter

end
verse3 = [num2str(m(end)),' is our (c) value.'];
disp (verse3)
verse = ['There were ' num2str(i), ' iterations done'];
disp (verse)
verse2 = ['The error is ', num2str(error(end))];
disp (verse2)
Here is my regula falsi code
clear all; clear clc;
g = 9.81; %acceleration m/s^2
m = 68.1; %mass, kg
t = 20; % time, seconds
f = @(c) g*m./c.*(1-exp(-c/m*t))-93.71;
c = 2:20;
plot (c, f(c))
xlabel('c = 2:20')
ylabel('Velocity formula in terms of c')
title('Plot of velocity function with respect to c')
a = 4; b = 8;
error = 1;
mold = 1;
SF = 6;
i = 1;
while (1)
  m = (a*f(b)-b*f(a))/(f(b)-f(a));
  mbis(i) = m;
  if f(a)*f(m)<0;
      b = m;
  else
      a = m;
  end
  error = abs ((m-mold)/m);
  if error < 0.5*10^-SF;
      break
  end
  mold = m;
  i = i + 1; %iteration counter
end
verse3 = [num2str(m(end)),' is our (c) value.'];
disp (verse3)
verse = ['There were ' num2str(i), ' iterations done'];
disp (verse)
verse2 = ['The error is ', num2str(error(end))];
disp (verse2)

Best Answer

Let me ask the other way around: Why do you assume that the number of iterations must be different?
Did you use the debugger already to compare the evaluations in the codes line by line?
The only difference is inside this block (and the corresponding block in the other branch):
   if F*f(m) > 0
     F = F/2;
   end
And does this condition occur at all?
Note: Do not shadow the important function "error" by a variable, because this leads to unexpected behavior frequently.
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