Let us consider the system of simultaneous equations.
such that a1 ,b2 , and c3 are the largest coefficients of x,y,z, respectively. So that convergence is assured. Rearranging the above system of equations and rewriting in terms of x, y, z, as:
let x0, y0, z0 be the initial approximations of the unknowns x, y and z. Then, the first approximation are given by
Similarly, the second approximations are given by
Proceeding in the same way, if xn , yn , zn are the nth iterates then
The process is continued till convergency is secured.
Note.In the absence of any better estimates, the initial approximations are taken as x0 = 0, y0 = 0, z0 = 0.
Examle 1. An approximate solution of the system 2x + 2y – z = 6, x – y + 2z = 8; – x + 3y+ 2z = 4 is given by x = 2.8, y’= 1, z = 1.8. Using the iterative method improve this solution.
Sol.Substituting the approximate value x′= 2.8, y′= 1, z′= 1.8 in the given equations, We get
Subtracting each equation in (1) from the corresponding given equations, we get
where xe= x – 2.8, ye= y –1, ze= z –1.8
Solving the equations (2), we get xe= 0.2, ye= 0, ze= 0.2
This gives the better solution x=3, y=1, z=2, which incidentally is the exact solution.
Example 2.Solve the following system of equation using Jacobi’s method
Start with the solution (2, 3, 0).
Sol.Given system of equation can be written in the folliwng form, if we assume, x0, y0, z0 as initial approximation:
Now if x0 = 2, y0 = 3, z0 = 0 , then
First approximation:
Second approximation:
Third approximation:
Fourth approximation:
Fifth approximation:
Hence, approximating solution after having some other approximations is (up to 3 decimal places)
Ans.
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