Perception বা দৃষ্টিভঙ্গি

"একটা উজ্জল সূর্য, সারিসারি গাছের পাতার ফাঁক দিয়ে একফালি সূর্যের আলো, পিচঢালা রাস্তার ব্যস্ত নগরী আর ব্যস্ত মানুষের পদচারণা, সব মিলিয়ে সুন্দর একটা দিন। আমার কল্পনা, আমিও কি তোমাদের মত এই সুন্দর দিনটি দেখতে পাই? না পাই না, কারণ আমি পারিনা । তোমাদের হাজার মানুষের সাহায্যে সৃষ্টিকর্তা আমাকে বাঁচিয়ে রেখেছেন। তারপরও আমি আজ অনেক আনন্দিত, আমি আজ তোমাদের চোখে স্বাধীন দেশের লাল সূর্য দেখতে পাই। এটাই আমার চূড়ান্ত বিজয়।" 

হ্যা, এটাই আমাদের চুড়ান্ত বিজয়, আমাদের গর্ব, আমাদের অহংকার, আমাদের সোনার বাংলা। তোমাদের প্রতি বিনম্র শ্রদ্ধা যারা আমাদের উপহার দিয়েছ এবং যারা উঁচু করে রাখছো আজও এই লাল সবুজের স্বাধীন পতাকা। সকল মুক্তিযোদ্ধা ও স্বাধীনতা যুদ্ধে শহীদদের প্রতি সম্মানে Artistry Reconciliation Crew Limited এর প্রযোজনায় এবং হাসিন আরেফিন খান-এর পরিচালনায় নির্মিত হয়েছে শর্টফিল্ম "Perception বা দৃষ্টিভঙ্গি" এর কেন্দ্রীয় চরিত্রে অভিনয় করেছেন Veet ChannelI top model 2011 এর জনপ্রিয় অভিনেত্রী ও মডেল অপ্সরা আলী। শর্টফিল্মটি ১৬ই ডিসেম্বর Artistry Reconciliation Crew Limited এর অফিসিয়াল ইউটিউব চ্যানেলে মুক্তি দেওয়া হবে বলে জানিয়েছেন ARc'র প্রেসিডেন্ট Hasin Arefin Khan। একই সাথে তিনি শর্টফিল্মটি দেখার জন্য সবাইকে আমন্ত্রণ জানিয়েছেন।

Title: দৃষ্টিভঙ্গি
Starring: Opshora Ali
Direction: Hasin Arefin Khan
Editing: Ahmed Sabbir
Production Manager: Abdullah Al Noman
Team #ARc, HR Hossain Rabby, Abhijeet Kundu

Eid al Mawlid an Nabi ﷺ Mubarak everybody.

Eid al Mawlid an Nabi ﷺ Mubarak everybody. spread His Sunnah Mubaraks aka Love.

What is the difference between supersonic, ultrasonic, and infrasonic waves?

Though all three of these end with suffix 'sonic', but only infra sonic and ultra sonic are related to the frequency of the sound, 

1. Infrasonic: is sound wave with less than 20 hertz and is too low pitched for human ear to hear.
2. Ultrasonic: is sound wave with more than 20000 hertz and is too high pitched for human ear to hear. And Ultrasonic is a word to describe sounds that is at ultrasound. So, ultrasound is noun and ultrasonic is adjective.

Image Credit: www.dreamstime.com

Now the other sonic, Supersonic is not related to frequency, rather is level of velocity of sound. Sound travels approximately at 330m/s. at STP. If any object travels at more than the speed of sound then we say that object is travelling at supersonic.

Supersonic jets are said to travel at speed greater than sound and can produce shock waves. Not really a eco-friendly thing. For example, Concorde is such plane which is suspended now due its noise and shock waves.

thank you.

Source code: N-Queen Problem in Backtracking using C [user friendly, visual friendly, OO]

#include < stdio.h >
#include < math.h >
#include < process.h >

int board[20];
int count;

void main()
{
int n, i, j;
// n= number of queens

void queen(int row, int n);

printf("N-Queen's using Backtracking\n");
printf("Pick a number for Queen [preferably no less than 4]: ");
scanf("%d", &n);
queen(1, n);
//trace using backtrack
printf("\n\n\n\n\n");

}


/*Function to print solution of n-queen's problem*/
void print_board(int n)
{
int i, j;
printf("\n\n solution %d:\n\n", ++count);
//number of solution

for (i= 1; i<= n; i++)
{
printf("\t%d", i);
}
for (i= 1; i<= n; i++)
{
printf("\n\n%d", i);
for (j= 1; j<= n; j++)
//for n*n board
{
if (board[i] == j)
printf("\tQ");
//Queen at i,j position
else
printf("\t-");
//empty slot
}
}
}
/*Function to check for the conflicts for approaching location. returns 1 for no no conflict, 0 otherwise*/
int place(int row, int column)
{
int i;
for (i= 1; i<= row -1; i++)
{
//checking for column and diagonal conflicts
if (board[i] == column)
return 0;
else
if (abs(board[i] -column) == abs(i -row))
return 0;
}
//no conflicts hence Queen can be placed
return 1;
}


/*Function to reach and check next free slot for next possible location for the Queen*/
void queen(int row, int n)
{
int column;
for (column= 1; column<= n; column++)
{
if (place(row, column))
{
board[row]= column;
//no conflicts so place queen

if (row == n)//dead end
print_board(n);  
//printing  board configuration
else //try with next position
queen(row +1, n);
}
}
}

special thanks to course mate: Sakib Shahid.

Concrete Mathematics Exercise Solution: Chapter 5 [Binomial Coefficients]

Derivation: 

Concrete Mathematics Exercise Solution: Chapter 5 [Binomial Coefficients] Basic Practice Problem: Form an Old Exam

Derivation: [assignment]:

Concrete Mathematics Exercise Solution: Chapter 5 [Binomial Coefficients] Basic Practice Problem: A Sum Involving Two Binomial Coefficients

Derivation: [assignment]:

Concrete Mathematics Exercise Solution: Chapter 5 [Binomial Coefficients] Basic Practice Problem: A Sum With Three Factors

Derivation: [assignment]:

Concrete Mathematics Exercise Solution: Chapter 5 [Binomial Coefficients]

Derivation: [assignment]:

Concrete Mathematics Exercise Solution: Chapter 5 [Binomial Coefficients]

Derivation: [assignment]:

Concrete Mathematics Exercise Solution: Chapter 5 [Binomial Coefficients]

Derivation: [assignment]:

Concrete Mathematics Exercise Solution: Chapter 5 [Binomial Coefficients]

Derivation: [assignment]:

Concrete Mathematics Exercise Solution: Chapter 5 [Binomial Coefficients]

Derivation:

Concrete Mathematics Exercise Solution: Chapter 5 [Binomial Coefficients]

Derivation: 

Concrete Mathematics Exercise Solution: Chapter 5 [Binomial Coefficients]

Derivation: 

Concrete Mathematics Exercise Solution: Chapter 5 [Binomial Coefficients]

Derivation: 

Concrete Mathematics Exercise Solution: Chapter 5 [Binomial Coefficients]

Derivation: 

Concrete Mathematics Exercise Solution: Chapter 5 [Binomial Coefficients]

Derivation: 

Concrete Mathematics Exercise Solution: Chapter 1[problem no: 13].

Question: 1.13: What’s the maximum number of regions definable by zig-zag lines, 

each of which consists of two parallel infinite half-lines joined by a straight segment?

Solution:

** click and open the photo for better view.

Concrete Mathematics Exercise Solution: Chapter 1[problem no: 11].

Question: 1.11: A Double Tower of Hanoi contains 2n disks of n different sizes, two of each size. As usual, we’re required to move only one disk at a time, without putting a larger one over a smaller one.

1. How many moves does it take to transfer a double tower from one peg to another, if disks of equal size are indistinguishable from each other?
2. What if we are required to reproduce the original top-to-bottom order of all the equal-size disks in the final arrangement? [Hint: This is difficult–it’s really a “bonus problem.”]

Solution:

for a: 

for b: 

** click and open the photo for better view.

Concrete Mathematics Exercise Solution: Chapter 1[problem no: 2].

Question: 1.2: Find the shortest sequence of moves that transfers a tower of n disks from the left peg A to the right peg B, if direct moves between A and B are disallowed. (Each move must be or to or from the middle peg. As usual, a larger disk must never appear above a smaller one.)

Solution:

** click and open the photo for better view.