Inverse Matrix Computation

Matrix A Represented by

Reference - Link

Happy Learning!!!

Matrix and Determinants (Basics)

Back to School and basics. These posts are for my on-line references.

Matrix

• Rectangular Array of Numbers in rows and columns
• Example - [5,2,-3]
• Order of Matrix is represented as Rows X Columns

Types of Matrices

• Row matrix (1 Row, any number of columns)
• Column matrix (1 Column, Multiple Rows)
• Diagonal matrix (Square matrix, Except diagonal elements every other elements are 0)
• Scalar matrix (Square matrix & Diagonal matrix in which all diagonal elements are same)
• Identity matrix - Denoted by I - Diagonal Elements are 1 (Square & Diagonal Matrix)
• Transpose of matrix - Matrix where rows and columns are interchanged

        [ 1, 1, 1 ]

A  = [ 2, 2, 2 ]

        [ 3, 3, 3 ]

Transpose is

A' =   [ 1, 2, 3 ]

          [ 1, 2, 3 ]

         [ 1, 2, 3 ]

Addition of Matrices

• They should be of same order
• Add Corresponding elements

A =   [2,3,5]

         [5,7,-2]

        [5,3,0]

B =    [7,-1,5]

          [0,2,3]

         [7,5,2]

Result ( Add Corresponding elements in same positions)

A + B =     [9,2,10]

         [5,9,1]

               [12,8,2]

Subtraction (similar to addition)

• Order needs to match

A = [7,-2]

       [0,3]

B = [0,2]

[3,5]

A - B = [7,-4]

          [-3,-2]

Scalar Multiplication

• Multiplying constant with a Matrix
• Every Element of Matrix Multipled

c = [3,5]

[-2,-10]

-2c =  [-6,-10]

  [4,20]

Matrix Multiplication

• A (m x n)
• B (n x p)
• Columns in a (n) = Number of Rows in B (n)

A = [3,5]

[7,2]

[2,3]

B = [-2,5]

[3,7]

AB = Operate First Row (Operate) Multiple with First Coulmn

A = [3,5] --->

[7,2]

[2,3]

Select Column 

B = [-2,5] 

[3,7]  

  = [ 3 X -2 + 5 X 3,  3 X 5 + 5 X 7 ]

[ 7 X -2 + 2 X 3,  7 X 5 + 2 X 7 ]

[ 2 X -2 + 3 X 3,  2 X 5 + 3 X 7 ]

 = [9,50]

[-8,49]

[5,31]

Matrix Multiplication is not commutative

Determinant of Square Matrix

+  -

A = [5,6]

[3,-4]

|A| = [Multiply Principal Diagonal Elements ] - [Subtract the Next Diagonal Elements]

= (5 X -4) - (3 X 6)

      = -20 - 18

      = -38

Determinant of 3 X 3 Matrix

        +,-,+

A =  [3,-2,1]

       [2,3,4]

       [2,5,4]

= +3 X [3,4] - (-2) X [2,4] + 1 X [2,3]

                  [5,4]               [2,4]           [2,5]

= 3(12-20) + 2 (8-8) + 1(10-6)

       = -24 + 0 + 4

       = -20

References - Link

Happy Learning!!!

Mobile Test Automation Startups

Interesting start-ups coming up in this space

• AppThwack
• AppliTools
• Testim

Other high visible companies include saucelabs, browserstack, perfecto mobile etc..

Happy Learning!!

Weekend Tech Talks

Excellent Talk on Android Testing and Automation Fundamentals

 

Good Notes / Screenshots from Session

Why Automated Testing, What does it Solve ?

What are pros / cons of Automation vs Manual Test Efforts ?

How to use Record / Play back tools ?

Mobile testing options Emulators / Devices ?

Evaluating a Commercial Tool ?

Happy Learning!!!

Setting up Jmeter Code base on Windows

Today Dinesh & myself had a good learning time in setting up Jmeter code base. There are not too many blogs / notes. This is a basic draft capturing the steps at high level. Good one for Windows background developers :).

1. Download Jmeter Zip code from Github
2. Create Project with same name. Eclipse - eclipse-jee-kepler-R-win32-x86_64
3. Setup Java Project

4. Set Ant Perspective

5. Execute Download Jars option as Ant Build (Run as Ant Build)

6. Download all the JAR files from link https://www.bouncycastle.org/latest_releases.html (Below mentioned versions)

Output path specified as below

7. Java Compiler Settings

8. Following code changes done for non matching jars

9. Below value set at Code Level

Happy Learning!!!

Interesting Sites

Two new interesting sites

Security Tools and Market Share of them - @ sectoolmarket 

Collection of useful tech talks available @ techtalkshub 

Happy Learning!!!

VodQA Presentation

My VodQA presentation slides

Leveraging Functional Tools and AWS for Performance Testing from ThoughtWorks



Happy Learning!!!

Good Interview Questions

Engineering Management Interview Questions

Interview Questions for Software Development Managers and Leaders

Hiring & interviews

Build the Skills You Need to Qualify – Part 1: How to Get Any Job You Want

Questions for Candidates to Ask in an Interview

10 Minutes a Day to Your Dream Job

Perspectival Interviewing

Note to self: how to be really productive?

Happy Learning!!!

Testcomplete - VBScript Notes

Tip #1
Change browser locale setting using registry edit. IE browser locale changes

'Browser language local setting function

Sub SetLanguage_FR()

Set wshShell = CreateObject( "WScript.Shell" )

wshShell.RegDelete "HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\International\AcceptLanguage"

wshShell.RegWrite "HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\International\AcceptLanguage", "fr-FR", "REG_SZ"

Set wshShell = Nothing

End Sub

Tip #2

Dictionary object example in VBScript

Sub CreateDictionaryExample()

'Dictionary Adding Values

 set ExpectedValues = CreateObject("Scripting.Dictionary")

   ExpectedValues.add "label17", "User Name:"

   ExpectedValues.add "label23", "Password:"

   ExpectedValues.add "label2", "Please enter Details"

   ExpectedValues.add "Btnlogin", "Submit"

  'Dictionary Listing Values

   nofElemtns = ExpectedValues.Count

   keys = ExpectedValues.Keys()

     for i=0 to nofElemtns-1

        k = keys(i)

        v = ExpectedValues.Item(k)

        Call Log.Message(k & ": " & v)

     next

End Sub 

Tip #3 - Disable windows pop up 'Your computer is at Risk' feature. 

This link . was useful to fix group policy changes

Tip #4 - Vbscript Kill all browser instances

This stackoverflow code snippet link was useful 

Happy Learning!!!

Good Read - Managing your IT career in 30's

Great Read from Quora. Usually I share my readings / learnings. This post was compelling, practical to manage work in 30s.

Read Quote of Michael O. Church's answer to What do software developers age 30 and over know now that they wish they had known in their 20s? on Quora


Read Quote of Michael O. Church's answer to Since programmers on average produce $500,000 for the tech companies they work for, why aren't they paid more? on Quora


Happy Reading!!!