MATLAB: How to code this Newton-Raphson and Secant Methods

iterationnumerical analysis

Determine the root of the given equation (3*x*e^x)-1=0 for x [0,1] using Newton-Raphson and Secant methods. Stop calculation after seven iterations. I've coded a code but I'm not sure it is right or not…
%f is non-linear function.
%fder is derivation of f.
%x0 is initial value of iteration.
%e is tolerance of f function.
%d is first condition tolerance value.
%y is error amount.
%max is maximum iteration number.
syms x
x0 = 0;
x1 = 1;
d = 0.000001;
e = 0.00001;
max = 7;
f = @(x) 3*x*exp(x)-1;
fder = @(x) 3*(exp(x)+exp(x))*x;
for iteration = 0:max
t = fder(x0); %to check the derivation is zero or not.
if abs(t)<e
disp('Derivation value is very close to zero, algorithm stops')
break
end
x1 = x0-(f(x0)/fder(x0));
error = abs(x1-x0);
odderror = 2*error/(abs(x1)+d);
x0 = x1;
y = f(x0);
if(error<d)||(odderror<d)||(abs(y)<e)
break
end
end
disp('Wanted root value')
x1
disp('Error amount')
y
disp('Iteration number')
iteration

Best Answer

The basic code is as follows. You can do other checks as desired.Your code looked ok, except you don't need symbolic variables and your fder function was missing a ')'.
x=0;
f = @(x) 3*x.*exp(x)-1;
fder = @(x) 3*(exp(x)+exp(x).*x);
for k=1:7%newton method
x=x-f(x)/fder(x);
end
y=[0,1];
for k=1:7%secant method
z=y(2);
y(2)=y(2)-f(y(2))*diff(y)/diff(f(y));
y(1)=z;
end
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