// CPP program to perform discrete cosine transform
#include <bits/stdc++.h>
using namespace std;
#define pi 3.142857
const int m = 8, n = 8;

// Function to find discrete cosine transform and print it
int dctTransform(int matrix[][n])
{
	int i, j, k, l;

	// dct will store the discrete cosine transform
	float dct[m][n];

	float ci, cj, dct1, sum;

	for (i = 0; i < m; i++) {
		for (j = 0; j < n; j++) {

			// ci and cj depends on frequency as well as
			// number of row and columns of specified matrix
			if (i == 0)
				ci = 1 / sqrt(m);
			else
				ci = sqrt(2) / sqrt(m);
			if (j == 0)
				cj = 1 / sqrt(n);
			else
				cj = sqrt(2) / sqrt(n);

			// sum will temporarily store the sum of
			// cosine signals
			sum = 0;
			for (k = 0; k < m; k++) {
				for (l = 0; l < n; l++) {
					dct1 = matrix[k][l] *
						cos((2 * k + 1) * i * pi / (2 * m)) *
						cos((2 * l + 1) * j * pi / (2 * n));
					sum = sum + dct1;
				}
			}
			dct[i][j] = ci * cj * sum;
		}
	}

	for (i = 0; i < m; i++) {
		for (j = 0; j < n; j++) {
			printf("%f\t", dct[i][j]);
		}
		printf("\n");
	}
}

// Driver code
int main()
{
	int img[n][m];
	for(int i=0;i<n;i++)for(int j=0;j<m;j++)cin>>img[i][j];
	dctTransform(img);
	return 0;
}

//This code is contributed by SoumikMondal
by

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About C++

C++ is a widely used middle-level programming language.

  • Supports different platforms like Windows, various Linux flavours, MacOS etc
  • C++ supports OOPS concepts like Inheritance, Polymorphism, Encapsulation and Abstraction.
  • Case-sensitive
  • C++ is a compiler based language
  • C++ supports structured programming language
  • C++ provides alot of inbuilt functions and also supports dynamic memory allocation.
  • Like C, C++ also allows you to play with memory using Pointers.

Syntax help

Loops

1. If-Else:

When ever you want to perform a set of operations based on a condition If-Else is used.

if(conditional-expression) {
   //code
}
else {
   //code
}

You can also use if-else for nested Ifs and If-Else-If ladder when multiple conditions are to be performed on a single variable.

2. Switch:

Switch is an alternative to If-Else-If ladder.

switch(conditional-expression){    
case value1:    
 // code    
 break;  // optional  
case value2:    
 // code    
 break;  // optional  
......    
    
default:     
 code to be executed when all the above cases are not matched;    
}

3. For:

For loop is used to iterate a set of statements based on a condition.

for(Initialization; Condition; Increment/decrement){  
  //code  
}

4. While:

While is also used to iterate a set of statements based on a condition. Usually while is preferred when number of iterations are not known in advance.

while (condition) {  
// code 
}

5. Do-While:

Do-while is also used to iterate a set of statements based on a condition. It is mostly used when you need to execute the statements atleast once.

do {  
 // code 
} while (condition);

Functions

Function is a sub-routine which contains set of statements. Usually functions are written when multiple calls are required to same set of statements which increases re-usuability and modularity. Function gets run only when it is called.

How to declare a Function:

return_type function_name(parameters);

How to call a Function:

function_name (parameters)

How to define a Function:

return_type function_name(parameters) {  
 // code
}