Numerical Methods: (Bisect, Secant, False position, Newton Raphson) Error

I'm trying to find the root of a function using Bisect, False position, Secant, and Newton/Raphson methods

But I keep getting this error: Any idea how to fix the problem?

False Position

       i         xl          xu           xr           ea
  Undefined function or variable "ea".

Error in falsepos (line 28)
  b=[iter;xl;xu;xr;ea];

Error in Test_1 (line 21)
falsepos(y,0,20,0.005,100)

    >>

My code is:

   A=4002.24; %Average Entery Level 
    n=35; %Age of retirement 
    F=1500000; %Future Worth
    i=0.3125; %Annual Interest
    g=[0:.001:20]; %Geometric Gradient

    y=A.*((1-(1+g).^n).*(1+i).^-n./(i-g)).*((1+i).^n)-F; %Future Worth Formula
    plot(g,y),grid,title('Figure.1 Annual Raise'),xlabel('g'),ylabel('Future Worth')

    format long
    y=@ (g)A.*((1-(1+g).^n).*(1+i).^-n./(i-g)).*((1+i).^n)-F;

disp('Bisection')
bisect(y,0,20,0.005,100)
check_fp=y(ans)

disp('False Position')
falsepos(y,0,20,0.005,100)
check_fp=y(ans)

    % disp('Newton Raphson Method')
    % dy=@(x) A*((1-(1+x).^n.*(1+i).^-n)./(i-x).*(1+i).^n)-F; %derivative of y  
    % newtraph(y,dy,0.3,1,100)
    % check_fp=y(ans)

    disp('Secant')
    secant(y,.5,.4,1,100)
    check_fp=y(ans)

[Rik]

What is the code inside falsepos doing? From this I can only see that you are calling it with 5 inputs. Is it expecting 6 inputs? When I get these kinds of errors it is usually that.

Answer 1

[Jan]

The error message tells you, that the variable "ea" is not defined. You did not post the code of the corresponding function "falsepos", so we do not have a chance to guess the reasons.

You can use the debugger to find out, what's going on: Set a breakpoint in the concerned function and step through the code line by line. Then you can see, why the creation of "ea" is not reached - or perhaps it is a typo only.