Question

1) Explain the IDFT function in Matlab 2) Re-write a SCILAB script that performs the IDFT. 3) Test your program using the following input xk (6-1-40-1)); 4) Plot x 5) Compare the output of Matlab with the output of SCILAB

Answer 1

A6p1.cpp

#include<bits/stdc++.h>
#include <sys/time.h>
#include <pthread.h>
using namespace std;

const int N=60;
char ar[N];
int n_threads; //stores no. of threads
int curr_thread=0; //stores index(0 to n_thread-1) of thread

// intitialize function intializes ar[] with random character values between 'A'-'Z'
void initialize(){

for(int i=0;i<N;i++){
ar[i]='A'+rand()%26; // rand()%26 will generate random integer between 0-25, ('A'+generated integer) will create character between A-Z
}
  
}

// print function prints the string in ar[]
void print(){
  
for(int i=0;i<60;++i){
cout<<ar[i];
}
  
}

// Each thread computes 1/p_thread th part of array
void* fun(void* arg){
  

// the part of array to be computed can be determined by the curr_thread(thread index)
int s=curr_thread*(N/n_threads),e=(curr_thread+1)*(N/n_threads);

for(int i=s;i<e;++i){
int x=ar[i]-'A';
x=25-x;
ar[i]=x+'a';
}
  
curr_thread++;
  
}

int main(int argc,char *argv[]){
  
n_threads=argv[1][0]-'0'; // get the no. of threads to be used from command line argument
  
cout<<"using "<<n_threads<<" threads\n\n";
  
initialize(); // initialize the character array

// print the original string
cout<<"original upper case string:\n";
print();
cout<<"\n\n";
  
pthread_t threads[n_threads];
  

// Creating threads
for(int i=0;i<n_threads;++i){
pthread_create(&threads[i],NULL,fun,(void *)NULL);
}
  

// joining threads i.e. waiting for all threads to complete
for(int i=0;i<n_threads;++i){
pthread_join(threads[i],NULL);
}
  

// print the final string
cout<<"complementary lower case string:\n";
print();
cout<<"\n\n";
  
}

A6p2.cpp

#include<bits/stdc++.h>
#include <sys/time.h>
#include <pthread.h>
using namespace std;

const int N=60; //no. of elements in array
const int r=5; //no. of rows
const int c=12; //no. of columns
int ar[r][c];
int n_threads; //stores no. of threads
int curr_thread=0; //stores index(0 to n_thread-1) of thread

// intitialize function intializes ar[] with random int values between 1-49
void initialize(){
  
srand(time(0));

for(int i=0;i<r;i++){
for(int j=0;j<c;++j){
ar[i][j]=(rand()%49)+1; // rand()%26 will generate random integer between 0-48, (1+generated integer) will create integer between 1-49
}
}
  
}

// print function prints the elements ofar[]
void print(){
  
for(int i=0;i<r;i++){
for(int j=0;j<c;++j){
cout<<ar[i][j]<<' ';
}
cout<<'\n';
}
  
}

// Each thread computes 1/p_thread th part of array
void* fun(void* arg){

// the part of array to be computed can be determined by the curr_thread(thread index)
int s=curr_thread*(N/n_threads),e=(curr_thread+1)*(N/n_threads);

for(int i=s;i<e;++i){
int r_i=i/c,c_i=i%c;
int x=ar[r_i][c_i];
ar[r_i][c_i]=x*x;
}
  
curr_thread++;
  
}

int main(int argc,char *argv[]){
  
n_threads=argv[1][0]-'0'; // get the no. of threads to be used from command line argument
  
cout<<"using "<<n_threads<<" threads\n\n";
  
initialize(); // initialize the array
  

// print the original array
cout<<"original array:\n";
print();
cout<<"\n\n";
  
pthread_t threads[n_threads];
  

// Creating threads
for(int i=0;i<n_threads;++i){
pthread_create(&threads[i],NULL,fun,(void *)NULL);
}
  

// joining threads i.e. waiting for all threads to complete
for(int i=0;i<n_threads;++i){
pthread_join(threads[i],NULL);
}
  

// print the final array
cout<<"updated array:\n";
print();
cout<<"\n\n";
  
}

make file(name of make file should be "Makefile")

all: A6p1 A6p2
A6p1: A6p1.cpp
g++ A6p1.cpp -l pthread -o A6p1
A6p2: A6p2.cpp
g++ A6p2.cpp -l pthread -o A6p27