Mathematical Methods (10/24.539)

VI. Numerical Solution of Algebraic Equations

Example 6.1 - Illustration of the Gauss Elimination Method

Problem Description:

Given the following system:

Determine the solution vector using the Gauss Elimination Method.

Problem Solution:

The various steps in the Gauss Elimination Method are as follows:

Step 0 -- form augmented matrix

Step 1 -- i = 1 perform partial pivoting

Step 2 -- i = 1 normalize pivot equation

Step 3+4 -- multiply eqn. i = 1 by 6 and subtract from eqn. j = i+1 = 2

Step 3+4 -- multiply eqn. i = 1 by 0 and subtract from eqn. j = i+2 = 3

Step 1 -- i = 2 perform partial pivoting

Step 2 -- i = 2 normalize pivot equation

Step 3+4 -- multiply eqn. i = 2 by 4 and subtract from eqn. j = i+1 = 3

Stop elimination phase since i = 2 = N-1 = 2

Step 5 – evaluate the last element of the vector

Step 6 – evaluate all other elements (in reverse order)

Therefore the final result is

.

10/24.539 Lecture Notes by Dr. J. R. White, UMass-Lowell (updated August 1998).

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