Study-Unit Description

Study-Unit Description


CODE MAT3712

 
TITLE Partial Differential Equations and Calculus of Variations

 
UM LEVEL 03 - Years 2, 3, 4 in Modular Undergraduate Course

 
MQF LEVEL 6

 
ECTS CREDITS 5

 
DEPARTMENT Mathematics

 
DESCRIPTION - Partial differential equations:
- First order quasi-linear equations
- Method of characteristics
- One dimensional wave equation, d’Alembert’s solution.

- Elliptic equations:
- Gravitation
- Laplace’s equation
- Poisson’s equation
- Harmonic functions.

- Calculus of variations:
- Motivating examples
- Continuous and piecewise differentiable solution
- The Euler-Lagrange equation
- Problems with fixed and non-fixed endpoints
- Problems with Constraints
- Necessary conditions for a minimum and corner conditions.

Study Unit Aims:

Linear partial differential equations are ubiquitous in mathematical physics; for example, classical gravitation, electrostatics, heat, diffusion, and waves all obey such equations. This study unit starts with quasi-linear first order partial differential equations and the powerful method of characteristics that can be used to solve them. Second order equations are studied next. Some can be reduced to a couple of first order equations. Among the irreducible equations, the potential equation is considered, of which the Laplace equation is a special case. Its solutions are the harmonic functions, which are generalizations of the real and imaginary parts of holomorphic functions.

The second part of the study-unit is concerned with finding an optimal function that maximizes or minimizes a given integral constraint, for example, finding the shape of a roller-coaster which minimizes the time spent in falling. The remaining chapters treat variations on this basic problem, such as when there are constraints and/or variable endpoints, for example, to find that function with maximum area and a given length.

Learning Outcomes:

By the end of the study-unit, students will be able to:
- Solve a quasi-linear first order partial differential equations and reducible second order equations, such as the one-dimensional wave equation, using the method of characteristics;
- Use this method to solve general first order ordinary differential equations;
- Understand the main properties of harmonic functions, including the mean value theorem;
- Derive the Euler-Lagrange equation of an optimization problem;
- Solve such equations with integral constraints (such as areas or arclengths), or non-fixed endpoints.

Suggested Reading

- Sneddon I., Elements of Partial Differential Equations, McGraw-Hill, 1957.
- Haberman R., Elementary Applied Partial Differential Equations with Fourier Series and Boundary Value Problems, Prentice Hall, New Jersey, 3rd Edition, 1998.
- Farbon S., Partial Differential Equations for scientists and Engineers, Dover Publications, 1993.
- Clegg J.C., Calculus of Variations, Oliver and Boyd, 1968.
- Pars L.A., An Introduction to the Calculus of Variations, Heinemann, 1962.
- Pinch E.R., Optimal Control and the Calculus of Variations, Oxford University Press, 1993.

 
ADDITIONAL NOTES Follows from: MAT3711

Leads to: MAT5713, MAT5616

 
STUDY-UNIT TYPE Lecture

 
METHOD OF ASSESSMENT
Assessment Component/s Assessment Due Sept. Asst Session Weighting
Examination (2 Hours) SEM2 Yes 100%

 
LECTURER/S Joseph Muscat

 

 
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Units not attracting a sufficient number of registrations may be withdrawn without notice.
It should be noted that all the information in the description above applies to study-units available during the academic year 2024/5. It may be subject to change in subsequent years.

https://www.um.edu.mt/course/studyunit