Example 15.6 The formulation of many engineering problems leads to a system of algebraic equations. As
you will learn later in your math and engineering classes, there are a number of ways to solve a
set of linear equations. Solve the following set of equations using the Gauss elimination, by
inverting the [A] matrix (the coefficients of unknowns), and multiplying it by {b} matrix (the
values on the right hand side of equations). The Gauss elimination method is discussed in de-
tail in Section 18.5. Here, our intent is to show how to use MATLAB to solve a set of linear
equations.For this problem, the coefficient matrix [A] and the right-hand side matrix {b} are
We will first use the MATLAB matrix left division operator \to solve this problem. The \
operator solves the problem using the Gauss elimination. We then solve the problem using
the invcommand.>> A = [2 1 1;3 2 4;5 -1 3]
A =
211
324
5-13>> b = [13;32;17]
b =
13
32
17
>> x = A\b
x =
2.0000
5.0000
4.0000
>> x = inv(A)*b
x =
2.0000
5.0000
4.0000
------------------------------------------------------------3 A 4 £
211
324
5 13
§ and 5 b 6 •
13
32
17
¶
5 x 1 x 2 3 x 3 17
3 x 1 2 x 2 4 x 3 32
2 x 1 x 2 x 3 13
15.5 Matrix Computations with MATLAB 491
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