I want to convert my program in to a function......tried function but something is wrong....???

Here is my program. How to write its function??

Inputs and output are as indicated in program

clc
clear all
close all
%=======================Inputs to the program==============================
f = @(x) x.^2+54/x;
k=1;
x(k)=1;
a=x(k);
e=0.1;
%============================Main program=================================
if abs(x(k))>0.01
dx=0.01*abs((x(k)));
else
dx=0.0001;
end

for m=1:inf
D1=(f(a+dx)-f(a-dx))/(2*dx);
D2=(f(a+dx)-2*f(a)+f(a-dx))/(dx)^2;
x(k+1)=a-(D1/D2);
a=x(k+1);       % Program Output after m iterations
C1=(f(a+dx)-f(a-dx))/(2*dx);

if abs(C1)<e
break
else
k=k+1; 
end
end
%================================END=======================================
%===========Progrm output is the final value of 'a'========================

Answer 1

[Walter Roberson]

f=inline(eqn);

However, you have

a=x(k);

and other references to x(k) when you have no x defined.

Answer 2

[Image Analyst]

You need two function lines if you're going to put this in one m-file. One for the test program, and one for your function:

function TestMyFunction()
clc
clear all
close all
%=======================Inputs to the program==============================
f = @(x) x.^2+54/x;
k=1;
x(k)=1;
a=x(k);
e=0.1;
% Now have TestMyFunction() call MyFunction()
new_a = MyFunction(f,k,x,a,e);

function a = MyFunction(f,k,x,a,e)
% Code for it....

Again, that can be all in one m-file, or you can use two separate m-files if you want.

[Maruti Patil]

I want in the function in the following format,(i.e i want to directly specify values and it should show final value of 'a'

[a] = MyFunction('x.^2+54/x',1,1,0.1)

for this I coded in the following format

function [a] = MyFunction(eqn,k,a,e)
a=x(k);
f=inline('eqn');
if abs(x(k))>0.01
dx=0.01*abs((x(k)));
else
dx=0.0001;
end

for m=1:inf
D1=(f(a+dx)-f(a-dx))/(2*dx);
D2=(f(a+dx)-2*f(a)+f(a-dx))/(dx)^2;
x(k+1)=a-(D1/D2);
a=x(k+1);       % Program Output after m iterations
C1=(f(a+dx)-f(a-dx))/(2*dx);

if abs(C1)<e
break
else
k=k+1; 
end
end

Please tell me where i am doing mistake