Difference between revisions of "Linear Systems in Matlab"
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See the discussion of [[LinearAlgebra|linear algebra]] for help on writing a linear system of equations in matrix-vector format. There is also help on [[Matlab_Arrays#Creating Arrays in Matlab|creating matrices and vectors]] in MATLAB. | See the discussion of [[LinearAlgebra|linear algebra]] for help on writing a linear system of equations in matrix-vector format. There is also help on [[Matlab_Arrays#Creating Arrays in Matlab|creating matrices and vectors]] in MATLAB. | ||
− | The simplest way of solving a system of equations in MATLAB is by using the '''\''' operator. Given a matrix '''A''' and a vector '''b''', we may solve the system using the following MATLAB commands | + | The simplest way of solving a system of equations in MATLAB is by using the '''\''' operator. Given a matrix '''A''' and a vector '''b''', we may solve the system using the following MATLAB commands: |
<source lang="matlab"> | <source lang="matlab"> | ||
x = A\b; | x = A\b; |
Revision as of 07:46, 25 August 2008
Contents
Solving Linear Systems of Equations in MATLAB
This section discusses how to solve a set of linear equations in MATLAB. See the discussion of linear algebra for help on writing a linear system of equations in matrix-vector format. There is also help on creating matrices and vectors in MATLAB.
The simplest way of solving a system of equations in MATLAB is by using the \ operator. Given a matrix A and a vector b, we may solve the system using the following MATLAB commands:
x = A\b;
Example
Consider the following set of equations:
These can be easily solved by hand to obtain .
To solve the system of equations using MATLAB, first rewrite these in a matrix-vector form as
Once in matrix-vector form, the solution is obtained in MATLAB by using the following commands:
A = [ 5 6; 3 1 ]; % define the matrix
b = [ 0; -5 ]; % define the vector
solution = A\b; % solve the system of equations.
In this example, solution is a column vector whose elements are x and y:
Matrix Inverse
Note that we can also form the inverse of a matrix,
This can be done in MATLAB as illustrated by the following:
A = [ 5 6; 3 1 ];
b = [ 0; -5 ];
Ainv = A^-1; % calculate the inverse of A
solution = Ainv*b; % calculate the solution
We could also calculate A-1 by
Ainv = inv(A); % entirely equivalent to A^-1.
Sparse Systems
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Linear Systems using the Symbolic Toolbox
Occasionally we may want to find the symbolic (general) solution to a system of equations rather than a specific numerical solution. The symbolic toolbox provides a way to do this.
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