Introduction to OpenCossan and to Object Oriented Programming … · 2016-12-06 · PHP M.Broggi...

CDT - Next Generation Nuclear, University of Manchester

27nd October 2014

Introduction to OpenCossan and to Object OrientedProgramming in MATLAB

Matteo Broggi

E: [email protected]: www.liv.ac.uk/risk-and-uncertaintyT: +44 (0)1925 864849

Institute for Risk and Uncertainty

A MEMBER OF THE RUSSELL GROUP

M.Broggi University of Liverpool 27nd October 2014 1 / 31

OpenCOSSAN History and developments

COSSANHistory and developments

1985 ISPUD (Importance sampling using design points)2006 - 2011 development of next generation of COSSAN2011 COSSAN (hosted at University of Liverpool)2012 First Release of OpenCossan

Transfer of stochastic simulation methods into engineering practice



OpenCossanIntuitive and Flexible toolbox

Programmed object oriented fashion in MATLAB R©Modular Framework: easy to use/reuse components



OpenCossanIntuitive and Flexible toolbox

Programmed object oriented fashion in MATLAB R©Modular Framework: easy to use/reuse components


OpenCOSSAN High Performance capability

OpenCossanParallelization solutions

1 Loop parallelismshared memory multi-coreuse Matlab parfor command

2 Job parallelismDistributed memory clusterindependent jobs sent throughGridEngine

3 Hybrid Job+Loop parallelismEach job start a pool of 12 Matlabworkers


OpenCOSSAN Algorithm and tools

Algorithms and toolsAdvanced Monte Carlo Simulation

Importance SamplingLine SamplingSubset Simulation

Pf =∫IF (x) gX

fX(x)gX(x)

dx

Pf = 1N∑N

k=1 IF (X(k))w(X(k))

Recent advances

Patelli, E.; Pradlwarter, H. J. & Schueller, G. I.

On Multinormal Integrals by Importance

Sampling for Parallel System Reliability

Structural Safety, 2011, 33, 1-7−1 0 1 2 3 4 5

−1

0

1

2

3

4

5

U1

U2

Moderately non−linear limit state functions − Efficient IS

g1g2

g1⋂

g2

samples ∈ g1 ∩ g2

samples /∈ g1 ∩g2

Intersection point





Pf = 1NL

∑NLi=1 p(i)

f

Pf = 1NL

∑NLi=1 Φ(−c(i))

Recent advances

de Angelis, Patelli, Beer, Advanced linesampling for efficient robust reliabilityanalysis Structural Safety, submitted





Pf = P

(m⋂

i=1

Fi

)P(F1)

m−1∏

i=1

P(Fi+1|Fi)



Surrogate (meta) model

Approximation of input/outputrelations with simplemathematical expression

Response surfaceKrigingArtificial Neural NetworksPolyharmonic Splines

Great reduction in computationaltime


Object Oriented Programming Introduction to OOP

Procedural Programming

The programming paradigm that we are most familiar withA program is a list of instructions for the computer to perform toaccomplish a given taskComponents of a program are code (subroutines or functions)and dataNo association between functions and the data on which theyoperateLanguages examples: FORTRAN, C, BASIC



Object Oriented Programming

Programming paradigm that uses the concept of objects thatunite data (saved as in structure fields) with associatedfunctionsEnsures that the correct functions are called by the correct dataExtreme modularity of the codeObject are used to interact with each otherAllows for a more natural, human readable codeEasier code maintenance and avoid code duplication

If you copy-paste blocks of code, you are doing it wrong!!!

Languages: C++, Objective-C, Java, C], Perl, Jscript, Python,PHP



Generic concepts

Class: blueprint for creating objects, defining properties andmethods, as well as default values/behaviourObject : instance of a class that has a specific state (properties)and behaviour (methods)Properties: data associated with an objectMethods: functions defined in a class and associated with anobjectInheritance: object or class (subclass) derived from anotherobject or class (superclass)


Object Oriented Programming OOP in MATLAB

Class component

A class is defined in a .m file named as the class.

classdef blockContains class definition, class attributes, and definessuperclasses

properties blockDefines all properties to be associated with a class instanceDefines attributes of all properties and default valuesMultiple property blocks for different property attributes

methods blockDefines methods associated with the class and their attributesFirst method is “special”, must have the same name as the class,and is called constructorMultiple method blocks for different method attributes



Classdef block

Block delineated by classdef <class name> till endContains all the other sub-blocks ( properties, methods, etc.)No code before classdef

No code after end



Properties

Properties are variablesassociated a particular classDefined in specialproperties blockCan be multiple propertiesblocks, each with ownattributesExamples of attributes1:

Access (Set-/Get-)DependentHidden

1http:

//www.mathworks.co.uk/help/matlab/matlab_oop/property-attributes.html


http://www.mathworks.co.uk/help/matlab/matlab_oop/property-attributes.html



Properties



1http:






Properties



1http:

//www.mathworks.co.uk/help/matlab/matlab_oop/property-attributes.htmlM.Broggi University of Liverpool 27nd October 2014 12 / 31




Properties



1http:






MethodsMethods are MATLAB functions associated with a particularclassDefined in special methods blockCan be multiple methods blocksCan be stored in separate files in a folder named as the class(together with main .m class file)Type of methods2:

Ordinary methods - functions that act on one or more objects(plus additional data) and return a new object or some computedvalueConstructor methods - special function that creates the objectsof a classDestructor methods - function called when instance of class isdeleted (used mainly with handle objects)Statics methods - functions associated with a class that do notact on class objects

2http:

//www.mathworks.co.uk/help/matlab/matlab_oop/how-to-use-methods.htmlM.Broggi University of Liverpool 27nd October 2014 13 / 31

http://www.mathworks.co.uk/help/matlab/matlab_oop/how-to-use-methods.html





2http:







2http:







2http:







2http:





MethodsAccessing methods

All non-static methods must accept the class instance (i.e.,object) as their first argumentStatic methods are called by referencing to the class name onlyMethods can be accessed in two ways

Directly passing the class instance as the first argumentUsing the . operator with the class instance

the class instance is implicitly passed as the first argument of themethod

More on this through practical examples...



Type of Objects

Two fundamental type of Objects available in MATLABValue objectsHandle objects

Value objectRepresent entities that are not unique (e.g.: numeric values)If the variable is reassigned, a copy of the original object iscreatedIf the variable is passed to a function, the function must returnthe modified object

Handle objectRepresent a reference to a set of dataIf the a copy is created, the same data is accessedIf the variable is passed to a function that modifies it, it is notnecessary to return the object



Type of Objects






Type of Objects






Type of ObjectsValue vs. Handle object behaviour









Example

Hands-on exampleSome concept of MATLAB object oriented programming will beexplained through some (partially completed) examples. Theexamples will be completed either through the lecture or as anassignement.

Simple class: rectangleProperties and methodsConstructor and error checking

Child class: squareMore “involved” class: Triangle

Constructor as property/value pairsDependent properties

Flexibility through OOP: the prism class



Simple class: RectangleProperties and Constructor



Simple class: RectanglePublic and Private Methods



Child class: squareInheritance



Let’s complicate things a bitTriangles

As we know from Geometry, a triangle can be defined in manyways by giving

three sidestwo side and the angle between themone side and two anglesand many more...

All the geometric properties are dependent between one andanother!A class must be able to cope with all these possibilities ofdefining a triangle

A simple constructor is not sufficient anymoreWe need to specify which property we are setting and assign thevalueThe other dependent properties must be determined from thegiven data



Class TriangleProperties



Class TriangleConstructor with pairs property/value



Class TriangleEfficient reutilization of methods



Class TriangleDependent properties get methods and Static methods



Triangle

Assignment 1Complete the Triangle class to support the definition of a triangleusing other combination of data. Check if the user passes too manyinputs and assign the right values to the public properties!



OOP FlexibilityPrism class

An object can be assigned as a property to another object.



OOP FlexibilityPrism class

An object can be assigned as a property to another object.All the public properties and methods will be accessible (noneed to recode them!)Using methods from other classes allows for easy to read andstreamlinde code



Prism

Assignment 2Expand the Prism class to support also non-right Prisms. Changethe Prism class so that the right prism is a child class of prism.



Abstract classes

Abstract classes are classes identified by the Abstract attributeAn abstract class serves as a basis (superclass) for a group ofrelated subclassesAn abstract class can define abstract properties and methodsthat every subclasses must implement.Each subclass can implement the concrete properties andmethods in a way that supports their specific requirements.Abstract classes can define properties and methods that arenot abstract.Abstract classes pass on their concrete members throughinheritance.



Abstract classes

Assignment 3Create an abstract class Shape and change Rectangle and Triangleso that they inherit from Shape. Is it possible to simplify the Prismconstructor by introducing Shape?

Assignment 4Create a new class inheriting from Shape from scratch and check ifit works with Prism out-of-the-box



Abstract classes

Assignment 3Create an abstract class Shape and change Rectangle and Triangleso that they inherit from Shape. Is it possible to simplify the Prismconstructor by introducing Shape?

Assignment 4Create a new class inheriting from Shape from scratch and check ifit works with Prism out-of-the-box



For more help:http://www.mathworks.co.uk/help/matlab/

object-oriented-programming.html

In-line MATLAB help and documentationGoogle!


http://www.mathworks.co.uk/help/matlab/object-oriented-programming.html

http://www.mathworks.co.uk/help/matlab/object-oriented-programming.html

Date post:	08-Jul-2020
Category:	Documents
Upload:	others
View:	0 times
Download:	0 times

Introduction to OpenCossan and to Object Oriented Programming … · 2016-12-06 · PHP M.Broggi...

Documents