500 likes | 716 Views
ECIV 301. Programming & Graphics Numerical Methods for Engineers Lecture 14 Elimination Methods. Objectives. Introduction to Matrix Algebra Express System of Equations in Matrix Form Introduce Methods for Solving Systems of Equations Advantages and Disadvantages of each Method.
E N D
ECIV 301 Programming & Graphics Numerical Methods for Engineers Lecture 14 Elimination Methods
Objectives • Introduction to Matrix Algebra • Express System of Equations in Matrix Form • Introduce Methods for Solving Systems of Equations • Advantages and Disadvantages of each Method
Last Time Matrix Algebra Rectangular Array of Elements Represented by a single symbol [A]
Row 1 Row 3 Column m Column 2 Last Time Matrix Algebra n x m Matrix
3rd Row 2nd Column Last Time Matrix Algebra
Last Time Matrix Algebra 1 Row, m Columns Row Vector
Last Time Matrix Algebra n Rows, 1 Column Column Vector
Main Diagonal Last Time Matrix Algebra If n = m Square Matrix e.g. n=m=5
Last Time Matrix Algebra Special Types of Square Matrices Symmetric: aij = aji
Last Time Matrix Algebra Special Types of Square Matrices Diagonal: aij = 0, ij
Last Time Matrix Algebra Special Types of Square Matrices Identity: aii=1.0 aij = 0, ij
Last Time Matrix Algebra Special Types of Square Matrices Upper Triangular
Last Time Matrix Algebra Special Types of Square Matrices Lower Triangular
Last Time Matrix Algebra Special Types of Square Matrices Banded
Last Time Matrix Operating Rules - Equality [A]mxn=[B]pxq n=p m=q aij=bij
Last Time Matrix Operating Rules - Addition [C]mxn= [A]mxn+[B]pxq n=p cij = aij+bij m=q
m=p Last Time Matrix Multiplication [A] n x m . [B] p x q = [C] n x q
Last Time Operations - Inverse [A] [A]-1 [A] [A]-1=[I] If [A]-1 does not exist [A] is singular
Last Time Operations - Trace Square Matrix tr[A] = Saii
Equations in Matrix Form Consider
# Equations = # Unknowns = n Square Matrix n x n
Solution of Linear Equations Consider the system
Solution of Linear Equations What is the characteristic? Express In Matrix Form Upper Triangular Solution by Back Substitution
0 Solution of Linear Equations Objective Can we express any system of equations in a form
Background Consider (Eq 1) 2*(Eq 1) (Eq 2) (Eq 2) Solution Solution !!!!!! Scaling Does Not Change the Solution
Background Consider (Eq 1) (Eq 1) (Eq 2) (Eq 2)-(Eq 1) Solution Solution !!!!!! Operations Do Not Change the Solution
Gauss Elimination Example Forward Elimination
Gauss Elimination Substitute 2nd eq with new
Gauss Elimination Substitute 3rd eq with new
Gauss Elimination Substitute 3rd eq with new