Nancyvarkey at 10:51, 18 March 2016

2016-03-18T10:51:30Z

Kaushik Datta at 09:57, 16 March 2016

2016-03-16T09:57:31Z

Kaushik Datta at 09:51, 16 March 2016

2016-03-16T09:51:22Z

Kaushik Datta at 09:46, 16 March 2016

2016-03-16T09:46:15Z

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Kaushik Datta at 08:33, 16 March 2016

2016-03-16T08:33:54Z

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Kaushik Datta: Created page with "{| border=1 ||'''Visual Cue''' ||'''Narration''' |- || Slide: '''Title Slide''' || Welcome to the spoken tutorial on '''Arrays''' as a part of the series on OpenModelica |-..."

2016-03-10T07:18:55Z

Created page with "{| border=1 ||'''Visual Cue''' ||'''Narration''' |- || Slide: '''Title Slide''' || Welcome to the spoken tutorial on '''Arrays''' as a part of the series on OpenModelica |-..."

New page

{| border=1
||'''Visual Cue'''
||'''Narration'''

|-
|| Slide:

'''Title Slide'''
|| Welcome to the spoken tutorial on '''Arrays''' as a part of the series on OpenModelica

|-
|| Slide:

Learning Objectives'''
|| In this tutorial, we are going to learn:

* How to declare '''arrays'''
* How to construct '''arrays'''
* How to use '''for''' and '''while''' loops
* How to use '''OMShell'''

|-
|| Slide:

'''System Requirements'''
|| To record this tutorial, I am using:

* '''OpenModelica 1.9.2''' Linux version

But, this process is identical in '''Windows''', '''Mac OS X''' or '''FOSSEE on ARM'''

|-
|| Slide:

Prerequisites
|| To understand and practice this tutorial, you need

* Knowledge of arrays in any programming language
* Knowledge of class definition in Modelica

|-
|| Slide:

'''Vector''' declaration (Add an example in the slide for declaration as well)
|| '''Vector''' is a one dimensional array

It has single index

Syntax for vector declaration is as shown. The example shown declares an array variable a whose size is '''2'''.

A vector can be constructed by including the elements in curly braces as shown.

This example defines vector '''a''' with '''2''' and '''3''' as its elements.

|-
|| Slide:

'''Vector Indexing'''
|| To access the elements of a vector, it is necessary to understand indexing.

The syntax for accessing an element is as shown.

Vector indexing starts from '''1'''.

Indices must be integers.

|-
|| '''Problem Statement'''
|| Let us develop a function named '''polynomialEvaluatorUsingVectors'''.

This function is an extension of '''polynomialEvaluator''' function discussed in previous tutorials.

We shall replace '''a,b,c''' in '''polynomialEvaluator''' function with a vector

|-
||
|| Please download and save all the code files available on our website.

For your convenience, '''polynomialEvaluator''' function is also made available.

|-
|| /* Switch to OMEdit */
|| Let me switch to '''OMEdit'''. It is now open in Welcome perspective.

I have opened the necessary files.

Note that the following classes are now open in OMEdit: '''functionTester''', '''polynomialEvaluatorUsingVectors''', '''matrixAdder''', '''polynomialEvaluator'''

|-
|| /* polynomialEvaluator */

'''protected parameter Real a = 1;'''

'''protected parameter Real b = 2;'''

'''protected parameter Real c = 1;'''

|| Now, let me view these classes. Double click on each icon.

Switch to '''polynomialEvaluator''' tab.

For more information on this function, watch the prerequisite tutorials.

|-
||
|| Click on '''polynomialEvaluatorUsingVectors''' tab.

|-
|| /* polynomialEvaluatorUsingVectors */

'''input Real x;'''

'''output Real fx;'''

|| Input and output variables are the same as '''polynomialEvaluator''' function.

|-
|| '''protected parameter Real a[3]''' = {1,2,1};
|| Parameters '''a,b''' and '''c''' in polynomialEvaluator are replaced by a real vector parameter named '''a'''.

|-
|| protected parameter '''Real a[3] = {1,2,1}''';
|| The size of this vector is '''3'''.

|-
|| protected parameter '''Real a[3] = {1,2,1}''';
|| Vector elements are specified in curly braces. They are separated by comma.

|-
|| '''algorithm'''

'''fx := a[1]*x^2 + a[2]*x + a[3];'''
|| This indicates the beginning of algorithm section.

The elements of vector a are accessed using their indices.

|-
|| '''algorithm'''

fx := '''a[1]'''<nowiki>*x^2 + a[2]*x + a[3];</nowiki>
|| a[1] is the first element in vector a.

It is the coefficient of '''x^2''' in the expression for '''fx'''.

|-
|| fx := a[1]*x^2 + '''a[2]*x + a[3];'''
|| Similarly, second and third elements of vector a are accessed.

|-
||
|| Rest of this function is same as '''polynomialEvaluator'''.

|-
||
|| Now, let us take a look at '''functionTester''' class

|-
|| Click on '''functionTester''' tab
|| Click on '''functionTester''' tab to switch.

|-
|| /* functionTester */

'''Real z;'''
|| '''z''' is a Real variable.

|-
|| '''z = polynomialEvaluatorUsingVectors(10);'''
|| '''polynomialEvaluatorUsingVectors''' function is called. The input argument is '''10'''.

|-
|| '''z = polynomialEvaluatorUsingVectors(10);'''
|| '''z''' is equal to the output returned by function call.

|-
|| Click on '''Simulate''' button
|| Click on '''Simulate''' button in the toolbar.

|-
|| /* Plotting perspective */

Click on '''z''' in variables browser
|| '''functionTester''' class is simulated.

Click on '''z''' in the variables browser.

'''z''' takes the value of '''f(x)''' at '''x = 10''', which is '''121'''

|-
|| Click on '''Modeling''' button
|| Click on '''Modeling''' button at bottom right.

|-
||
|| Let me go back to the slides.

|-
|| Slide:

'''for''' (Add another slide for syntax)

|| '''for''' loop is used to iterate statements a given number of times

'''for''' loop can be used in both algorithm and equation sections

The syntax of '''for''' loop is as shown with an example.

|-
||
|| Let me go back to '''OMEdit'''.

|-
||
|| Click on '''polynomialEvaluatorUsingVectors''' tab.

|-
|| /* polynomialEvaluatorUsingVectors */

'''fx := a[1]*x^2 + a[2]*x + a[3]; '''
|| To evaluate '''fx''', we are accessing the elements of vector '''a'''.

This can also be done using a for loop. Now, let us include a for loop in the algorithm section.

|-
|| Comment // '''fx := a[1]*x^2 + a[2]*x + a[3]; '''
|| Comment the assignment statement for '''fx''' in the algorithm section by inserting double slash.

|-
||
|| The for loop to be inserted has been provided in a text file named '''for-loop.txt'''. It is available on our website.

I have opened this file using '''gedit'''. Windows users may use notepad to open it.

|-
||
|| Let me go to '''gedit'''.

|-
||
|| Copy all the statements. Go back to '''OMEdit'''

|-
||
|| Press '''Enter'''.

Paste the for loop using '''Ctrl + V'''. Press '''Ctrl + S''' to save the function.

|-
|| // '''fx := 0;'''
|| Now, let me explain each statement.

This statement assigns '''fx '''an initial value of zero before the loop starts.

|-
|| // '''for i in 1:3 loop'''
|| Here, '''i''' serves as a loop counter. Loop runs until '''i''' is '''3'''.

It is not necessary to declare '''i''' before it is used.

|-
|| //''' fx := fx + a[i]*x^(3-i); '''
|| This statement iteratively adds terms of the polynomial '''f(x)'''.

|-
|| '''// end for;'''
|| This statement indicates the end of '''for''' loop

|-
||
|| Now, the function is complete. Let us use the class '''functionTester''' to test the function after modification.

|-
|| Click on '''functionTester''' tab
|| Click on '''functionTester''' tab. We have not made any changes to this class.

|-
|| Click on '''Simulate''' button
|| Click on '''Simulate''' button in the toolbar.

|-
|| /* Plotting perspective */
|| The class is simulated.

Click on '''z''' in '''variables browser'''. Value of '''z''' remains the same after changes made to the function.

|-
|| Switch to '''Modeling perspective'''
|| Click on '''Modeling''' button at bottom right.

|-
||
|| Let me go back to the slides.

|-
|| Slide:

'''while'''

|| '''while''' loop is used to iterate a set of statements until a given condition is satisfied.

'''while''' loop cannot be used in equation section.

'''for''' is frequently used as compared to '''while'''.

|-
|| Slide:

'''Arrays'''
|| '''Arrays''' may have more than one dimension.

They can constructed using vector notation.

2 dimensional arrays may be constructed using matrix notation as well.

|-
|| Slide:

'''Syntax'''
|| '''Syntax''' for array declaration and indexing is as shown.

|-
|| Slide:

'''Problem Statement'''
|| Let us write a class named '''matrixAdder''' which

adds '''myMatrix''' and adder matrices to give '''mySum'''.

'''myMatrix''' and adder matrices are as shown.

|-
||
|| Now, let me switch to '''OMEdit''' to demonstrate '''matrixAdder''' class. It is already open in '''OMEdit'''.

|-
|| /* Switch to OMEdit */
|| Click on '''matrixAdder''' tab.

|-
||
|| This class performs matrix addition by accessing each element individually.

|-
|| '''parameter Real[3, 2] myMatrix = {{1,2},{3,4},{5,6}}''';
|| '''myMatrix''' is a Real parameter array.

|-
|| '''parameter Real[3, 2] myMatrix = {{1,2},{3,4},{5,6}}''';
|| This represents array size. It has two dimensions. The size of first dimension is '''3'''.

Similarly, the size of second dimension is '''2'''

|-
|| parameter Real[3, 2] myMatrix = // '''{{1,2},{3,4},{5,6}}; '''//''' Highlight piecewise'''
|| '''myMatrix''' array is constructed using three vectors of two elements each. '''{1,2}''' represents the first vector.

Size of the vector is equal to size of second dimension of the array. Hence, size of second dimension of myMatrix is '''2'''.

Number of vectors is equal to the size of first dimension.

Higher dimensional arrays may be constructed similarly.

|-
|| '''parameter Real[3, 2] adder''' '''<nowiki>= {{1,0},{0,1},{1,0}};</nowiki>'''
|| '''adder''' matrix is similarly constructed.

|-
||
|| We need to access elements from two dimensions here.

A '''nested for''' loop is required.

|-
|| '''for i in 1:3 loop'''
|| This '''for''' loop runs through the first dimension of array.

|-
|| '''for j in 1:2 loop'''
|| This loop runs through the second dimension.

|-
|| '''mySum[i, j] := myMatrix[i, j] + adder[i, j]; '''
|| Corresponding elements of '''myMatrix''' and adder are added.

Elements of '''mySum''' array are produced from this addition.

|-
|| '''end for; '''

'''end for; '''
|| They represent the end of each '''for''' loop.

|-
|| Click on '''Simulate''' button
|| Click on '''Simulate''' button in the toolbar.

|-
|| /* Plotting perspective */
||''' variables browser''' shows each individual element of the array.

Click on '''myMatrix[1,1], adder[1,1]''' and '''mySum[1,1]''' in variables browser.

Note that '''mySum[1,1]''' is the sum of '''myMatrix[1,1]''' and '''adder[1,1]'''.

Hence, this result is correct. Let me delete the result.

|-
||
|| Let us go back to the slides.

|-
|| Slide:

'''Assignment'''
|| Try the following problems:

Write a function named '''vectorReversal''' that takes a vector as input and returns a vector with the order of elements reversed.

Write a function named '''matrixReversal''' that takes a matrix as input and returns a matrix with the order of elements in each row reversed.

Write a '''functionTester''' class to test these two functions

|-
||
|| This brings us to the end of this tutorial

|-
|| Slide:

About the '''Spoken Tutorial project'''
|| Watch the video available at the link shown below

['''http://spoken-tutorial.org/ http][http://spoken-tutorial.org/ ://][http://spoken-tutorial.org/ spoken][http://spoken-tutorial.org/ -][http://spoken-tutorial.org/ tutorial][http://spoken-tutorial.org/ .][http://spoken-tutorial.org/ org] /What\_is\_a\_Spoken\_Tutorial'''

It summarises the '''Spoken Tutorial''' project

If you do not have good bandwidth, you can download and watch it.

|-
|| Slide:

'''Spoken Tutorial''' Workshops
|| We conducts workshops using spoken tutorials

Give certificates

Please contact us

|-
|| Slide:

Forum
|| If you have questions in this tutorial, please visit the webpage mentioned.

|-
|| Slide:

'''Textbook Companion Project'''
|| We coordinate coding of solved examples from popular books. We give honorarium to contributors. Please visit our website.

|-
|| Slide:

'''Lab Migration Project'''
|| We help migrate labs from commercial simulators to OpenModelica.

|-
|| Slide:

'''Acknowledgements'''
|| Spoken Tutorial Project is supported by '''NMEICT, MHRD''', Government of India.

|-
|| Slide:

'''Thanks'''
|"| We thank '''OpenModelica''' development team for their support.

|-
||
|| Thank you for joining me in this tutorial. Goodbye!

|}

@@ Line 147: / Line 147: @@
 |-
 || protected parameter '''Real a[3] = {1,2,1}''';
-|| The elements of this vectors are included in curly braces as shown.
+|| The elements of this vector are included in curly braces as shown.
 The elements are separated by a '''comma'''.

@@ Line 36: / Line 36: @@
 || To understand and practice this tutorial:
-* you need knowledge of '''arrays''' in any programming language.
+* You need knowledge of '''arrays''' in any programming language.
 * You need to know how to define a '''class''' in '''Modelica'''.
@@ Line 48: / Line 48: @@
 '''Vector''' declaration (Add an example in the slide for declaration as well)
 || '''Vector''' is a one dimensional array.
-−
 It has single index.
@@ Line 398: / Line 398: @@
 || '''myMatrix''' array is constructed using three vectors of two elements each.
-'''{1,2}''' represents the first vector.
+* '''{1,2}''' represents the first vector.
-'''{3,4}''' is the second one and
+* '''{3,4}''' is the second one and
-'''{5,6}}''' represents the third vector.
+* '''{5,6}}''' represents the third vector.
 Size of each of this vectors is equal to size of second dimension of this array.