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% ****** False Position Method ********
clc;
clear all;
close all;
f=@(x) x*x*x - 4;
a=3;
b=2;
e=0.0001;
fprintf("Root : %f\n",f(a));
if f(a)*f(b)<0
  for i=1:100
    c=(a*f(b)-b*f(a))/(f(b)-f(a));
    fprintf("Root = %d\n",c);
    if abs(f(c)) < e
      break;
    endif
    if f(a) * f(c) < 0
      b=c;
    endif
    if f(b) * f(c) < 0
      a = c;
    endif
  endfor
else
  fprintf("There is no root");
end

% *******************Newton Raphson Method******************
clc;
clear all;
close all;
f = @(x) x^3 - 4;

df = @(x) 3*x^2;
x0 = 3;
e = 0.0001;
fprintf("Initial guess : %f\n",x0);
for i = 1:100
  x = x0 - (f(x0) / df(x0));
  fprintf("Root = %f\n",x);
  if abs(x - x0) < e
    break;
  endif
  x0 = x;
end

% **************** Secant Method ****************
f=@(x) x*x*x - 5*x+1;
x0 = 0;
x1 = 1;
t_error = 0.00001;

for i=2:100

  x2 = x1-((x1-x0)*f(x1))/(f(x1)-f(x0));
  fprintf("Root %d = %f\n",i,x2);

  if abs(x2-x1) < t_error
    break;
  endif

  x0=x1;
  x1=x2;
endfor

% **************** Elimination Method **************
A= input("Enter the co-efficient matrix:");
B= input("Enter the source matriux:");

N= length(B);

X=zeros(N,1);
AugMat=[A B]
for j=1:N-1
  for i=j+1 :N
    m= AugMat(i,j)/AugMat(j,j);
    AugMat(i,:)=AugMat(i,:)-m*AugMat(j,:);

  endfor
end
AugMat

X(N)=AugMat(N,N+1)/AugMat(N,N);
for k=N-1:-1:1
  X(k)=(AugMat(k,N+1)-AugMat(k,k+1:N)*X(k+1:N))/AugMat(k,k);
end
AugMat

% **************************Jordan Method***********************************

%jorden mathod
%Ingrdients
A = input('Enter your co-effcient matrix: ')
B = input('Enter source matrix: ')
N = length(B); %no of unknowns
X = zeros(N,1);
Aug = [A B]
for j=1:N %for columns
Aug(j,:) = Aug(j,:)/Aug(j,j)
for i=1:N % for rows
if i~=j
m = Aug(i,j)
Aug(i,:) = Aug(i,:) - m*Aug(j,:)
   end
 end
end

% *********Jordan Method Another Way************ 

function [x,err]=gauss_jordan_elim(A,b)
A = [1 1 1;2 3 5; 4 0 5] % input for augmented matrix A
b = [5 ; 8; 2] % intput for matrix B
[n,m]=size(A); % finding the size of matrix A
err =0; % calculation of error
x=zeros(n,1); % calling fuction zero
if n ~= m
    disp('error: n~=m'); % displaying error if found
    err = 1;
end % end of the scope of if
if length(b) ~= n  % finding the legth of matrix B
    disp('error: wrong size of b'); % displaying error, if found
    err = 2;
else
    if size(b,2) ~= 1
        b=b';
    end % end of the scope of if-else
    if size(b,2) ~= 1
        disp('error: b is a matrix'); % displaying erron in matrix B
        err = 3;
    end
end
if err == 0
    Aa=[A,b];
    for i=1:n
        [Aa(i:n,i:n+1),err]=gauss_pivot(Aa(i:n,i:n+1));
        if err == 0
            Aa(1:n,i:n+1)=gauss_jordan_step(Aa(1:n,i:n+1),i);
        end
    end
    x=Aa(:,n+1);
end
A=0;
function A1=gauss_jordan_step(A,i) % calling of fuction function

[n,m]=size(A); % determination of size of matrix A
A1=A; % assigning A to A1
s=A1(i,1);
A1(i,:) = A(i,:)/s;
k=[[1:i-1],[i+1:n]];
for j=k
    s=A1(j,1);
    A1(j,:)=A1(j,:)-A1(i,:)*s;
end % end of for loop
function [A1,err]=gauss_pivot(A) % calling of fucntion
[n,m]=size(A); % finding the size of matrix A
A1=A; % process of assigning
err = 0; % error flag
if A1(1,1) == 0
    check = logical(1); % logical(1) - TRUE
    i = 1;
    while check
        i = i + 1;
        if i > n
            disp('error: matrix is singular');
            err = 1;
            check = logical(0);
        else
            if A(i,1) ~= 0 & check
                check = logical(0);
                b=A1(i,:);      % process to change row 1 to i
                A1(i,:)=A1(1,:);
                A1(1,:)=b;
            end
        end
    end
end

%*****************Seidal***********************
%seidal mathod
A = input('Enter a Co-efficient Matrix A: ');
B = input('Enter a source Matrix B (column vector): ');
P = input('Enter initial Guess Vector: ');
n = input('Enter no of iterations: ');
e = input('Enter your tolerance: ');
N = length(B);
X = zeros(N,1);
Y = zeros(N,1);

for j=1:n
    for i=1:N
        X(i) = (B(i)/A(i,i)) - (A(i,[1:i-1,i+1:N])*P([1:i-1,i+1:N]))/A(i,i);
    end
    fprintf('Iteration no %d\n', j)
    disp(X)
    if norm(Y-X) < e
        fprintf('Convergence reached at iteration %d\n', j);
        break;
    end
    Y = X;
end

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