Linear Equations - Computing and Numerical Analysis - Exam, Exams of Mathematical Methods for Numerical Analysis and Optimization

Main points of this exam paper are: Linear Equations, Gauss Elimination, Newton – Raphson, False – Position, in terpolation, Extrapolation, Quadratic Splines

Typology: Exams

2012/2013

Uploaded on 04/13/2013

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Cork Institute of Technology
Bachelor of Engineering (Honours) in Mechanical Engineering – Stage 2
Bachelor of Engineering in Mechanical Engineering – Stage 2
(NFQ – Level 8)
Autumn 2005
Computing and Numerical Analysis
(Time: 3 Hours)
Instructions
Answer any FOUR questions.
All questions carry equal marks.
Examiners: Dr. R. Sheehy
Mr. J. E. Hegarty
Prof. J. Monaghan
Q1. (a) Describe the Gauss Elimination Method for solving a system of linear equations. (9 marks)
(b) Write a program which uses the Gauss Elimination Method with partial pivoting for
solving a system of linear equations. (10 marks)
(c) Briefly describe the main pitfalls in using Gauss Elimination and list some techniques for
improving the solution. (6 marks)
Q2. (a) Describe any two of the following methods for obtaining roots of an equation:
(i) Newton – Raphson
(ii) Bisection
(iii) False – Position (6 marks)
(b) Explain the terms convergence and stability as applied to numerical methods for
obtaining roots and show that
(
)
(
)
()()
2
.
xf
xfxf
< 1 is a necessary condition for
convergence of Newton – Raphson Method. (8 marks)
(c) Outline the general structure of a program for locating single roots of an Equation.
(6 marks)
(d) The displacement of a structure is defined by y = 10e0.5t Cos2t for damped oscillation.
Estimate the time required for the displacement to decrease to 4. (5 marks)
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Cork Institute of Technology

Bachelor of Engineering (Honours) in Mechanical Engineering – Stage 2

Bachelor of Engineering in Mechanical Engineering – Stage 2

(NFQ – Level 8)

Autumn 2005

Computing and Numerical Analysis

(Time: 3 Hours)

Instructions Answer any FOUR questions. All questions carry equal marks.

Examiners: Dr. R. Sheehy Mr. J. E. Hegarty Prof. J. Monaghan

Q1. (a) Describe the Gauss Elimination Method for solving a system of linear equations. (9 marks) (b) Write a program which uses the Gauss Elimination Method with partial pivoting for solving a system of linear equations. (10 marks) (c) Briefly describe the main pitfalls in using Gauss Elimination and list some techniques for improving the solution. (6 marks)

Q2. (a) Describe any two of the following methods for obtaining roots of an equation: (i) Newton – Raphson (ii) Bisection (iii) False – Position (6 marks)

(b) Explain the terms convergence and stability as applied to numerical methods for

obtaining roots and show that f (( f^ x ′)( ).^ xf ′)( )^2 x < 1 is a necessary condition for

convergence of Newton – Raphson Method. (8 marks)

(c) Outline the general structure of a program for locating single roots of an Equation. (6 marks)

(d) The displacement of a structure is defined by y = 10e 0.5t^ Cos2t for damped oscillation. Estimate the time required for the displacement to decrease to 4. (5 marks)

Q3. (a) Briefly describe the terms: (i) Interpolation (ii) Extrapolation. (6 marks)

(b) Given the data: x 3.0 4.5 7.0 9. f ( x ) 2.5 1.0 2.5 0.

Calculate the f (5) using a 2nd^ order Lagrange Polynomial. (8 marks)

(c) Fit Quadratic Splines to the same data and use your results to estimate f (5). (11 marks)

Q4. (a) Use central difference formulae to estimate the first, second and third derivative of f (x) = x 2 at x = 0.5 using step size h = 0.5. (9 marks)

(b) Use Richardsons extrapolation to obtain a O (h^4 ) estimate of the first derivative at x = 0.5. (8 marks)

(c) Show that the Differential Operator D is related to the Difference Operator ∆

by: D = 1 h^ λ n ( 1 +∆)

hence, show that the n th^ derivative D N^ fi ≈ (^) hNN f i (^1) (8 marks)

Q5. (a) Briefly describe the rationale behind: (i) Newton Cotes Integration formulae (ii) Gauss Quadrature. Derive the two points Gauss Quadrature formula. (8 marks) (b) Outline the general structure of a program for Numerical Integration using either Gauss Quadrature or a Newton Cotes formulae (e.g. Simpsons ⅓ Rule). (8 marks) (c) Use two point Gauss Quadrature to evaluate the integral of f (x) = Sin x between the limits x = 0 and x = π. (5 marks) (d) Explain Römberg Integration. (4 marks)